Question

Help complete the square
f(x)=-x^2-4x-8

Answer 1

start with \(f(x)=-(x^2+2x)-18\) then go to
\[f(x)=-(x+1)^2+k\] to find \(k\) replace \(x\) in the original function by \(-1\) i.e. \(k=f(-1)\)

Answer 2

\(f(-1)=?\)

Answer 3

to me it looks like it would be -1

Answer 4

oops
\[f(-1)=-(-1)^2-2\times (-1)-18=-1+2-18=-17\] so
\[f(x)=-(x+1)^2-17\]

Answer 5

f(x)=-(x-1)^2-17

Answer 6

should be plus one, not minus one

Answer 7

\[f(x)=-(x+1)^2-17\] you can check by multiplying out to see that it is right