Respuesta :

Answer:

4

Step-by-step explanation:

To find f(-1)g(-1) which is f(-1)*g(-1), first, we must find what are values of f(-1) and g(-1) first which can be found by substituting x = -1 in both functions.

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

Now we know that f(-1) is 2, next, we find g(-1).

[tex]\displaystyle{g(-1) = 3(-1)+5}\\\\\displaystyle{g(-1)=-3+5 = 2}[/tex]

Now we know that g(-1) is 2 too. Since the question wants to find f(-1)g(-1), therefore 2*2 = 4.

Hence, the answer is 4.

Esther

Answer:

D) 4

Step-by-step explanation:

Given functions:

f(x) = x² + 1

g(x) = 3x + 5

Here, we're asked to find the value of both functions when the value of x is -1. Then, we multiply the functions in order to find the value of f(-1)•g(-1).

Note: f(-1) • g(-1) is equivalent to (f • g)(-1).

Method 1: f(-1) • g(-1)

Find the value of each function when x = -1.

f(-1) = (-1)² + 1 ⇒ f(-1) = 1 + 1 ⇒ f(-1) = 2

g(-1) = 3(-1) + 5 ⇒ g(-1) = -3 + 5 ⇒ g(-1) = 2

Multiply the functions together.

f(-1) • g(-1) ⇒ 2 • 2 ⇒ 4

Method 2: (f • g)(-1)

First, multiply the functions.

⇒ (x² + 1) • (3x + 5) [ Simplify using the Distributive Property: (a + b) • (c + d) = ac + ad + bc + bd. ]

⇒ x²(3x) + x²(5) + 1(3x) + 1(5)

⇒ 3x³ + 5x² + 3x + 5

Now, substitute -1 as the value of x.

⇒ 3(-1)³ + 5(-1)² + 3(-1) + 5 [ Exponents first. }

⇒ 3(-1) + 5(1) -3 + 5 [ Multiply the numbers. ]

⇒ -3 + 5 - 3 + 5 [ Simplify. ]

⇒ 4

Therefore, the product of both functions when x = -1 is 4.

Learn more about multiplying functions here:

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