Question

If s(x) = 2-x2 and t(x) = 3x, which value is equivalent to (s•t) (-7)?

Answer 1

For this case we have the following functions:

`s (x) = 2-x ^ 2 t (x) = 3x`
When multiplying the functions we have:

`(s * t) (x) = s (x) * t (x)`
Substituting values we have:

`(s * t) (x) = (2-x ^ 2) * (3x)`
Rewriting we have:

`(s * t) (x) = 6x - 3x ^ 3`
We evaluate the new function for x = -7

`(s * t) (-7) = 6 (-7) - 3 (-7) ^ 3 (s * t) (-7) = -42 - 3 (-343) (s * t) (-7) = -42 + 1029 (s * t) (-7) = 987`
Answer:
A value that is equivalent to (s • t) (-7) is:

`(s * t) (-7) = 987`

Answer 2

The given functions are
s(x) = 2 - x²
t(x) = 3x

By multiplying the both functions

∴ (s * t ) (x) = (2-x²) * (3x) = 6x - 3x³

To find (s * t ) (-7), substitute with x = -7 in the resultant function of the multiplication

∴ (s * t ) (-7) = 6 * (-7) - 3* (-7)³ = 987