Question

Find f(-2) if f(x) = 2x2 + kx + 2 and f(1) = 3.

Answer 1

need help

Answer 2

replace x by 1 and solve
\[f(1)=2+k+2=3\] for k

Answer 3

k=-1?

Answer 4

no it is wrong

Answer 5

We find what k is by plugging 1nfor x into the original function and setting the result equal to 3:
2*1^2 + k*1 + 2 = 3, so k = -1, and the function is\[f(x) = 2x^{2} - x + 2.\]We evaluate this function at x = -2:
f(-2) = 8.

Answer 6

so what is its' result?

Answer 7

I glitched. f(-2) = 12.

Answer 8

why?

Answer 9

Did you get k = -1?

Answer 10

yes

Answer 11

looks like if you solve larger less than twice the smaller. make x the larger then we get
\[2+k+2=3\] you get
\[k=-1\] yes? so now you have
\[f(x)=2x^2-x+2\] and if you want
\[f(-2)\] you compute
\[f(-2)=2(-2)^2-(-2)+2\]

Answer 12

oh ok

Answer 13

You use the information to find the value of f(-2).

Answer 14

ok I understand now.Thanks

Answer 15

:^)