Question

Let $a=-1$, let $b=3$, and let $c=-5$. Calculate $b(abc+5ab)+b(c+a)$.

Answer 1

Answer: $b(abc+5ab)+b(c+a)$ = - 18

Explanation:

If $a = $ - 1, $b = $3 and $c = $- 5, then

abc = - 1 × 3 × - 5 = 15

5ab = 5 × - 1 × 3 = - 15

Then,

$b(abc+5ab) = 3(15 - 15)

Opening the brackets, it becomes

3 × 0 = 0

(c + a)$ = - 5 - 1 = - 6

Then,

b(c+a)$ = 3 × - 6 = - 18

Therefore,

$b(abc+5ab)+b(c+a)$ = 0 + (- 18)

$b(abc+5ab)+b(c+a)$ = 0 - 18 = - 18