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Consider these functions:

f(x)= -1/2x^2 + 5x
g(x)= x^2 + 2

What is the value of f(g(-2))?

Respuesta :

jacobEwing

Answer:

The value of f(g(-2)) is 12.

Step-by-step explanation:

We'll start by solving g(-2):

[tex]g(-2)\\= (-2)^2 + 2\\= 4 + 2\\= 6[/tex]

Now we can take that value and plug it into function f:

[tex]f(6)\\= \frac{-1}{2}6^2 + 5 * 6\\= -36/2 + 30\\= -18 + 30\\= 12[/tex]

Alternatively, you can work out a new single function that in itself describes f(g())

[tex]f(g(x)) = -\frac{1}{2}g(x)^2 + 5g(x)\\= -\frac{1}{2}(x^2 + 2)^2 + 5(x^2 + 2)\\= -\frac{1}{2}(x^4 + 4x^2 + 4) + 5x^2 + 10\\= -\frac{1}{2}x^4 - 2x^2 - 2 + 5x^2 + 10\\= -\frac{x^4}{2} + 3x^2 + 8[/tex]

and try plugging -2 into the new function

[tex]= - \frac{-2^4}{2} + 3(-2)^2 + 8\\= -16 / 2 + 3 * 4 + 8\\= -8 + 12 + 8\\= 12[/tex]

The value of f(g(-2)) for the given expression will be 12.

What is an expression?

Expression is a finite combination of symbols that is well-formed according to rules that depend on the context.

We have,

f(x) = [tex]\frac{-1}{2} x^2[/tex]  + 5x

And,

g(x) = x² + 2

Now,

For, x = -2,

i.e.

g(x) = x² + 2

Now,

Substituting the value of x = -2,

g(-2) = (-2)² + 2

On solving,

We get,

g(-2) =  6

Now,

For, f(g(-2)),

f(x) = [tex]\frac{-1}{2} x^2[/tex]  + 5x

i.e.

Substituting the value of g(-2) =  6,

i.e.

f(g(-2)) = [tex]\frac{-1}{2} (g(-2)^2)[/tex] + 5(g(-2))

i.e.

f(g(-2)) = [tex]\frac{-1}{2} *6^2[/tex]  + 5 * 6

On solving,

We get,

f(g(-2)) = -18 + 30

i.e.

f(g(-2)) = 12

So, the value of f(g(-2)) for the given expression is 12.

Hence, we can say that the value of f(g(-2)) for the given expression will be 12.

To know more about expression click here

https://brainly.com/question/953809

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