Grade 8 Algebraic Expressions Quiz 1 draws its questions at random from 40 questions across these topics:
A few of the question types, with full solutions, so you know what to expect.
Variables. The pattern is \(3,\; 6,\; 9,\; 12,\; \ldots\) and the rule is \(3n\), where \(n\) is the term number. What is the 20th term?
Answer: \(60\)
The rule \(3n\) means \(3 \times n\).
For the 20th term, \(n = 20\): \(3 \times 20 = 60\).
Tip: \(320\) comes from writing the digits side by side. \(3n\) always means multiply.
Variables. Thabo's age is \(x\). His sister is 4 years older. Write an expression for his sister's age.
Answer: \(x + 4\)
"4 years older" means add 4 to Thabo's age.
Tip: \(4x\) would mean four times his age, which is a very different claim.
Variables. Why is \(x\) called a variable?
Answer: Because its value can change
A variable is a letter standing in for a number.
If Thabo is 12 then \(x = 12\); if he is 14 then \(x = 14\). The value varies.
Expression or equation. Which of these is an equation?
Answer: \(2x + 3 = 11\)
An equation has an equal sign. An expression does not.
Tip: Expressions get simplified. Equations get solved.
Expression or equation. Which of these is an expression?
Answer: \(2y - 7\)
Look for the equal sign. Only \(2y - 7\) has none.
Tip: An expression is a phrase; an equation is a full sentence.