Introduction to Algebra (2021)

This post is about an Introduction to Algebra.

The basics of algebra include numbers, variables, constants, expressions, equations, linear equations, and quadratic equations. Further, it involves the basic arithmetic operations of addition, subtraction, multiplication, and division within the algebraic expressions.

Introduction to Algebra

We work with numbers in arithmetic, while in algebra we use numbers as well as Alphabets such as $A, B, C, a, b$, and $c$ for any numerical values we choose. We can say that algebra is an extension of arithmetic. For example, the arithmetic sum of two numbers $5+3=8$ means that the sum of numbers 5 and 3 is 8. In algebra, two numbers can be summed by the expression $x+y=z$ which is the general form that can be used to add any two numbers. For example, if $x=5$ and $y=3$ then $x+y$ will be equivalent to the left-hand side ($5+3$) and the summation of these numbers will be equivalent to the right-hand side $z$ which is 8.

In algebra all arithmetic operators such as $+, -, \times, =$ and $\div$, etc., can be used used.

For example, $x-y=z$ means that the difference between two numbers is equal to the number represented by the letter z. In algebra, many other notations used are the same as in arithmetic. For example,

$c=a\times b$ means that the product of two numbers represented by $a$ and $b$ is equal to the number $c$.

$x \times x \times x$ can be written as $a^4$.

Introduction to Algebra

From the above discussion, note that letters of the alphabet represent variables, and arithmetic operators (+, -, etc) represent the mathematical operations on a variable. The combination of numbers and letters of the alphabet is called an algebraic expression. For example, $8x + 7y$, $x+y$, and $7x^2+2xy-5y^2$ etc. are examples of expression.

Some important points to remember:

  • Algebra is like a toolbox for solving mathematics problems with unknowns. Instead of using specific numbers, we use letters like $x$, $y$, and $z$ to represent unknown values. These letters are called variables.
  • A variable is a quantity (usually denoted by letters of the alphabet) in algebraic expressions and equations, that changes from place to place, person, to person, and/or time to time. The variable can have any one of a range of possible values.
  • A factor that multiplies with a variable. For example, in $2x^3+3x=0$, $x$ is a variable, 2 is the coefficient of $x^3$, and 3 is the coefficient of $x$.

We learning algebra the following concepts are very important to understand the concepts used in algebra:

  • Variables are the building blocks, representing unknown numbers.
  • Expressions are combinations of variables, numbers, and mathematical operations (such as +, -, *, /) that do not necessarily have an equal sign (=).
  • Equations are statements (or expressions) with an equal sign that shows two expressions are equivalent. The equations are solved to find the value of the variable.
  • Inequalities are statements (or expressions) having “greater than” (>), “less than” (<), or “not equal to” (≠) symbols for making comparisons between expressions.

Real Life Applications of Algebra

  • Finances and Budgeting: Algebra helps you create formulas to track income, expenses, savings goals, and loan payments. You can set up equations to see how much extra money you’d have if you cut certain expenses or how long it’ll take to save for a down payment on a house.
  • Mixing and Ratios: Whether you’re baking a cake or mixing paint colors, algebra helps you determine the correct ratios of ingredients to achieve the desired outcome. You can set up proportions to find out how much water to add to a paint concentrate or how much flour you need to double a recipe.
  • Motion and Physics: From calculating travel time based on speed and distance to understanding the trajectory of a thrown ball, algebra forms the foundation for many physics concepts. You can use formulas to figure out how long it’ll take to drive somewhere at a certain speed or the angle needed to throw a basketball into the hoop.
  • DIY Projects and Home Improvement: From measuring lumber for a bookshelf to calculating the amount of paint needed for a room, algebra helps with planning and executing home improvement tasks. You can use formulas to find the area of a wall to determine how much paint to buy or calculate the volume of wood needed for a project.
  • Scientific Research and Data Analysis: Algebra is the backbone of many scientific formulas and equations used in research. It helps analyze data, identify trends, and make predictions.
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Estimation, Approximating a Precise Value 1

Estimation (Approximating a Precise Value) is very useful especially when someone wishes to know whether he/ she has arrived at a logical solution to a problem under study. It is useful to learn about how to estimate the total sum of a bill to avoid immediate overpayments. For example, one can estimate the total amount of shop (supermarket) receipts. The estimate of these receipts can be done by rounding the amount of each item to the nearest half and keeping a running total mentally from the first item to the last one.

Estimation of a Utility Bill

Suppose the following is a shop receipt, with the estimated amount and running total. Consider, the estimation, approximating a precise value for a utility bill.
Shop Item, Actual Amount, Estimated Amount, Running Total.

Shop ItemActual AmountEstimated AmountRunning Total
Item 14.504.504.50
Item 23.503.508
Item 31.31.59.5
Item 40.600.510
Item 52.95313
Item 62.85316
Item 71.601.5017.5
Item 82.75320.5
Item 92.42.523
Total22.4523 

From the above example, it can be observed that estimation is a process of finding an estimate of a value. It saves time and results in the nearest possible exact value. An estimate can be overestimated (when the estimate exceeds the actual value) and underestimated (when the estimate falls short of the actual value).

Estimation, Approximating a Precise Value

In some cases, an estimate can be performed to round all of the numbers that you are working to the nearest 10 (or 100 or 1000) and then do the necessary calculations. In everyday life, the estimation can be used before you solve a problem in an easier and faster way. It helps you to determine whether your answer is reasonable. Estimation is also useful when you need an approximate amount instead of a precise value.

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Absolute Error of Measurement

The absolute error of measurement is the difference between the measured value of an object and its true value.

When we measure an object, the measured value may be either a little more or a little lower than its true value, that is, an absolute error has occurred.
For example, if a scale (a measurement device) states the weight 10KG but you know the true weight is about 9KG, then the scale has an absolute error of 1KG ($ 10KG-9KG=1KG$).

This error may be caused by the scale used itself ‌ not measuring the exact amount of measurement you are trying to measure. For example, your measuring device may be accurate to the nearest KG. That is, if the weight is 9.6 kg, your scale may “round up” and give 10 kg. Thus, the absolute error is about $ 10KG-9.6KG=0.4KG$.

Absolute Error of Measurement

Mathematically, it can be described by the formula given below,
$ (\Delta X)=X_i-X$, where $ X_i$ is the measurement quantity by the device used and $X$ is the true value.

The measurement device may either little more or a little lower than the true value, the formula can be described in absolute form, that is
$$(\Delta X)=|X_i-X| $$

Absolute Error of a Measurement

‌Note that

  • If someones know the true value and the measured value, then the absolute error of measurement is just the subtraction of these numbers. However, sometimes, one may not know about the true value, one should use the maximum possible error as the absolute error.
  • Any possible measurement that one makes is ‌ an approximation, 100% accuracy of any measurement is impossible. It is also possible that if a measurement of the same object is made twice, then the two measurements may not be identical. Such ‌ differences between measurements (of the same object) are called variations in the measurement.
  • The absolute error of measurement does not provide any details about the graveness or importance of the error. For example, when measuring the distances between cities Kilometers apart, an error of a few centimeters is negligible. However, an error of centimeters when measuring a small piece of a machine is a ‌ significant error.
  • The largest possible absolute error of a measurement is always half of the value of the smallest unit used.
Types of Errors: Absolute Errors

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Basics of Ratios: Use and Application (2021)

This post will discuss some Basics of Ratios. The ratio is used to compare two quantities of the same kind. Consider in a group of 45 people, 15 of whom are females. Let us understand the Basics of Ratios from an example.

Example of Ratios

We can compare the number of males and the number of females in the group in two different ways,

  1. There are 15 more males than females in a group of people. We are comparing the number of males and the number of females in the group of people by finding their differences.
  2. The number of males in a group of people is twice that of females. We are comparing the number of males and the number of females by finding a fraction consisting of the number of males over the number of females. The fraction is $\frac{30}{15}$.

In the second method, the fraction obtained is an example of the ratio.

A ratio may be written with a colon symbol between the numbers. Therefore, the male-female ratio in the group of people can be written as 30:15 or $\frac{30}{15}$. It can be read as the ratio of 30 is to 15, or simply 30 to 15.

In general, the ratio of $a$ to $b$ can be written as $la:b$ or $\frac{a}{b}$, where $a$ and $b$ represent whole numbers and $b$ should not be zero. Since ratio $\frac{30}{15}=\frac{2}{1}$ or $30:15 = 2:1$. the $30:15$ and $2:1$ are called equivalent ratios.

Basics of Ratios

Note that the order in which the ratio is written is important. A ratio has no measurement units. It is only a number that indicates how many times, one quantity is as great as the other. For example, the male to the female ratio of 2:1 means that the number of males is twice the number of females. It can also be interpreted as the female to male of 1:2 or $\frac{1}{2}$ indicates that there are half as many females as males.

Ratios Formula Uses and Application

Application of Ratios

Ratios can also be used to compare more than two quantities. For example, three-men A, B, and C share the profit of a business. They receive say 5000, 3000, and 1000, respectively. The ratio of their share of the profit is 5000:3000:1000 or 5:3:1.

One can also find that either there is an increase or decrease in the ratio. For example, say if the number of teachers in a college is increased from 45 to 55, then the ratio “number of present staff” to “number of old staff” (or number of present staff: number of old staff) = $55:45 = 11:9$ or $\frac{\text{no. of present staff}}{\text{no. of old staff}} = \frac{55}{45}=\frac{11}{9}$.
This ratio can be interpreted as the number of teachers has been increased in the ratio 11:9 or $\frac{11}{9}$.

The application of ratios in various fields are:

  1. Finance (Financial rations, investment analysis)
  2. Business and Management (inventory management, marketing and sales, and human resources)
  3. Science and Engineering (Concentration and Ratios in Chemistry, Mixture Ratios, Scale and Proportion
  4. Everyday Applications (Recipes, Maps and Scales)
  5. Mathematics (Rates and Unit Costs, Proportions)

Remember, ratios are a versatile tool, and their specific applications can vary depending on the field and situation. However, their core principle of comparing quantities remains constant, making them a valuable asset for anyone seeking to analyze and understand the world around them.

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