Question

216. Factor and then calculate the value of the expression

a) a² + ab with a = 6.6, b = 3.4;


b) x2 - xu at x = 0.5, y = 2.5;


c) —5a² — 5ah at a = 4, x = -3

Answer 1

• a) 66
• b) -1
• c) -20

Explanation:

a) a² + ab = ?

→ (6.6)² + (6.6 × 3.4)

→ 43.56 + 22.44

→ 66

So, the answer is 66.

b) x² - xu = ?

→ (0.5)² - (0.5 × 2.5)

→ 0.25 - 1.25

→ -1

So, the answer is -1.

c) -5a² - 5ah = ?

→ -5(4)² - 5(4 × -3)

→ (-5 × 16) - (5 × -12)

→ -80 + 60

→ -20

So, the answer is -20.

Answer 2

• a) 66, b) - 1, c) - 20

Explanation:

Solve as below

a) a² + ab with a = 6.6, b = 3.4;

• a² + ab = a(a + b) = 6.6(6.6 + 3.4) = 6.6(10) = 66

b) x² - xu at x = 0.5, y = 2.5;

• x² - xu = x(x - u) = 0.5(0.5 - 2.5) = 0.5(- 2) = - 1

c) -5a² - 5ah at a = 4, h = -3;

• -5a² - 5ah = - 5a(a + h) = - 5(4)(4 - 3) = - 20(1) = - 20