Evaluate f(x) = -2x² -4 for x=3 A. -10 B. 10 C. -18 D. -22

2 answers:

8 0

$f(x) = -2x^2-4 \\ f(x) = -2(3)^2-4 [tex][plug in 3 into your x value][tex]\\ f(x)=-18-4[tex] [3 squared equals 9. Now multiply 9*(-2) = -18[tex]\\ f(x)=-22 [ -18-4]$

andrew-mc [135]3 years ago

3 0

F(x) = - 2 x² - 4 for x = 3

f(3) = - 2*3² - 4

f(3) = -2*9 - 4

f(3) = -18 -4

f(3) = -22

Answer D

hope this helps!

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Step-by-step explanation:

Problem 1

For the first problem, we first want to find y so that we can plug it into the expression.

We can use elimination method for the system of equations to solve.

3x+3y=21

3x-y=5

We subtract both equations to eliminate x.

4y=16 [divide both sides by 4]

y=4

Now that we know y, we can plug it into the expression.

$\frac{4}{2} -3$ [divide]

$2-3$ [subtract]

$-1$

We know that the answer is A.

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Problem 2

For the second problem, we need to know how to calculate percent error. The formula for precent error is $\frac{|measured-exact|}{exact} *100%$ . We know that the exact value is 80 because the buyer was supposed to given 80. 75 is the measured value because that was what the buyer was given.