Question

Taking x = 3, find the values of the following algebraic expressions.

(1) 5x − 3
(2) x²
(3) 2x³
(4) 5x² + x
(5) x² + 2x

Answer 1

(1) 5x − 3
Substituting the value of x in the given expression, we get:
5 × 3 − 3
= 15 − 3 (Performing multiplication first)
= 12

(2) x²
Substituting the value of x in the given expression, we get:
(3)² = 9

(3) 2x³
Substituting the value of x in the given expression, we get:
2(3)³
= 2 × 27 (Solving the simple brackets first)
= 54

(4) 5x² + x
Substituting the value of x in the given expression, we get:
5(3)² + 3
= 5 × 9 + 3 (Solving the simple brackets first)
= 45 + 3 (Performing multiplication first)
= 48

(5) x² + 2x
Substituting the value of x in the given expression, we get:
(3)² + 2 × 3
= 9 + 2 × 3 (Solving the simple brackets first)
= 9 + 6 (Performing multiplication first)
= 15