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Algebra - Solving Linear Equations

Grade 8IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

πŸ”‘Concepts

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Definition of a Linear Equation: An equation where the highest power of the variable (usually x) is 1.

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The Golden Rule of Algebra: Whatever operation you perform on one side of the equation, you must perform the exact same operation on the other side to keep it balanced.

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Inverse Operations: Use subtraction to undo addition, addition to undo subtraction, division to undo multiplication, and multiplication to undo division.

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Isolating the Variable: The goal is to get the variable alone on one side of the equals sign.

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Expanding Brackets: If an equation contains brackets, use the distributive law a(b+c)=ab+aca(b + c) = ab + ac before solving.

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Variables on Both Sides: Collect all terms containing the variable on one side and all constant numbers on the other side by adding or subtracting terms.

πŸ“Formulae

General form: ax+b=cax + b = c

Distributive Property: a(x+b)=ax+aba(x + b) = ax + ab

Fractional Equations: xa=bβ€…β€ŠβŸΉβ€…β€Šx=aΓ—b\frac{x}{a} = b \implies x = a \times b

Cross Multiplication: If \frac{a}{b} = rac{c}{d}, then ad=bcad = bc

πŸ’‘Examples

Problem 1:

Solve 4xβˆ’7=134x - 7 = 13

Solution:

x=5x = 5

Explanation:

Step 1: Add 7 to both sides to undo the subtraction (4x=204x = 20). Step 2: Divide both sides by 4 to isolate x (x=20/4=5x = 20 / 4 = 5).

Problem 2:

Solve 3(2x+1)=213(2x + 1) = 21

Solution:

x=3x = 3

Explanation:

Step 1: Expand the brackets (6x+3=216x + 3 = 21). Step 2: Subtract 3 from both sides (6x=186x = 18). Step 3: Divide by 6 (x=3x = 3).

Problem 3:

Solve 5xβˆ’4=2x+115x - 4 = 2x + 11

Solution:

x=5x = 5

Explanation:

Step 1: Subtract 2x2x from both sides to get all variables on the left (3xβˆ’4=113x - 4 = 11). Step 2: Add 4 to both sides (3x=153x = 15). Step 3: Divide by 3 (x=5x = 5).

Problem 4:

Solve x+42=7\frac{x + 4}{2} = 7

Solution:

x=10x = 10

Explanation:

Step 1: Multiply both sides by 2 to remove the denominator (x+4=14x + 4 = 14). Step 2: Subtract 4 from both sides (x=10x = 10).