Do you find yourself struggling with algebra? Not even sure what an expression is? This is probably the first time you've found random letters of the alphabet scattered around a math problem. Not sure what you need to do? Well, here is the guide for you.
Steps
Step 1. You need to understand what an unknown is
These letters that you see scattered haphazardly in the math expression are called unknowns. Each unknown is found in place of a number you don't know.
Example: in 2x + 6, the letter x is the unknown.
Step 2. You must understand what an algebraic expression is
An algebraic expression is a sequence of numbers and unknowns mixed with a certain number of mathematical operators (addition, multiplication, powers, etc.).
Here are some examples:
-
2x + 3y it is an expression. It is formed by adding the product of
Step 2. And x to the product d
Step 3. And y.
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2x it is also an expression. It is formed by the number
Step 2. and from the unknown x united by the mathematical operation of multiplication.
Step 3. You need to understand what it means to calculate the value of an algebraic expression
Calculating the value of an algebraic expression means replacing a fixed number with the unknown, or replacing the unknown with the given number.
For example, if you are asked to calculate 2x + 6 where x = 3, all you have to do is rewrite the expression by replacing each occurrence of x with 3. So, you get 2(3) + 6.
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Calculate the expression you got with:
2(3) + 6
= 2×3 + 6
= 6 + 6
= 12
Hence, 2x + 6 = 12 if x = 3.
Step 4. Try to calculate the value of expressions that contain more than one unknown
You must proceed in exactly the same way as you followed in the case of only one unknown; you have to repeat the procedure more than once.
If, for example, you were asked to calculate the value of 4x + 3y with x = 2, y = 6
- Replace x with 2: 4 (2) + 3y
- Replace y with 6: 4 (2) + 3 (6)
-
Solve the calculation:
4×2 + 3×6
= 8 + 18
= 26
Hence, 4x + 3y = 26 if x = 2 and y = 6
Step 5. Try to calculate the value of expressions that contain powers
Find the value of 7x2 - 12x + 13 if x = 4
- Replace x with 4: 7 (4)2 - 12(4) + 13
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Remember to follow the correct order of the operators: Parentheses, Exponents, Multiplication and Division, Addition and Subtraction, according to the acronym PEMDAS. Since the calculation of powers comes before that of multiplications, before multiplying or dividing, you must calculate the square of 4, and after having performed them, calculate the additions and subtractions.
So, with the power calculation you get, (4)2 = 16.
This step produces the expression 7 (16) - 12 (4) + 13.
-
Do multiplication or division:
7×16 - 12×4 + 13
= 112 - 48 + 13.
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Perform Addition or Subtraction:
112 - 48 + 13
= 77
Hence, 7x2 - 12x + 13 = 77 if x = 4.
