Question

If s(x) = 2 – x2 and t(x) = 3x, which value is equivalent to (s t)(-7)? A. -439 B. -141 C. 153 D. 443

Answer 1

Option (a) is correct.

`s(t(x))=-439`

Explanation:

Given :
`s(x) = 2- x^2` and
`t(x) = 3x`

We have to find the value of (s t)(-7) and choose the correct option from the given options.

Consider the given function
`s(x) = 2- x^2` and
`t(x) = 3x`

and we have to find the value of (s t)(x) at x = -7

We first find the value of (st)(x) that is s(t(x))

Thus,
`s(t(x))=2-(3x)^2`

Simplify,

`s(t(x))=2-9x^2`

We get, For x = -7 , we have,

`s(t(-7))=2-9(-7)^2`

Simplify, we have,

`s(t(-7))=2-441=-439`

Thus,
`s(t(x))=-439`

Answer 2

Answer: Option A -439

(s o t)(x)=s(t(x))
(s o t)(-7)=s(t(-7))
x=-7→t(-7)=3(-7)→t(-7)=-21
(s o t)(-7)=s(t(-7))=s(-21)
x=-21→s(-21)=2-(-21)^2=2-441→s(-21)=-439
(s o t)(-7)=s(t(-7))=s(-21)=-439
Answer: Option A -439