Can someone please help me on 7

B

Step-by-step explanation:

plug in 5

5^2-5(4)+7=12

Work Shown:

A.

f(x) = 3x-8

f(5) = 3*5-8 ... replace every x with 5; simplify with PEMDAS

f(5) = 15-8

f(5) = 7

We can cross choice A off the list since we got 7 as an output, instead of 12.

B.

f(x) = x^2-4x+7

f(5) = (5)^2-4(5)+7

f(5) = 25-4(5)+7

f(5) = 25-20+7

f(5) = 5+7

f(5) = 12

We got the output we wanted. So we can stop here.

If you're curious about the others, then,

C.

f(x) = -x+14

f(5) = -5+14

f(5) = 9

That doesn't work, so we cross choice C off the list.

D.

f(x) = |x-7|

f(5) = |5-7|

f(5) = |-2|

f(5) = 2

Choice D is crossed out as well.

So only choice B works.

x = ± 6i

step-by-step explanation:

x^2 = -36

take the square root of each side

sqrt(x^2) = sqrt(-36)

we know sqrt(ab) = sqrt(a) sqrt(b)

x = ±sqrt(36) sqrt(-1)

we know that sqrt (-1) = i

x = ± 6i

-2

7 - 9 = -2

reversed:

-2 + 9 = 7