Answer:
18
Explanation:
Using the product rule
Given
y = f(x). g(x) , then
= f(x). g'(x) + g(x). f'(x)
Here
f(x) =
⇒ f'(x) = 5
×
(2x + 3) , then
f'(x) = 10
g(x) =
⇒ g'(x) = 8
×
(x + 2) , then
g'(x) = 8
Thus
=
. 8
+
. 10
← factor expression
=
[ 8(2x + 3) + 10(x + 2)
=
(16x + 24 + 10x + 20)
=
(26x + 44)
Thus
( x = - 1)
=
×
× 18
= 1 × 1 × 18
= 18