Question

http://prntscr.com/axielm

Answer 1

any ideas?

Answer 2

well the formula to a perfect square trinomial is (x+a)(x+a)=x^2+2ax+a^2

Answer 3

so we have x^2+2ax+a^2
and we have x^2+4x+?

Answer 4

you can use the two equations to find a and use it to find the last term

Answer 5

lets take the middle terms of both equations
we have 2ax and 4x

we know both equations are equal since the first equation is the general form
so 2ax=4x
x's get canceled
and we have 2a=4
solve for a

Answer 6

a=2

Answer 7

Quite close but you want the final expression
\[x^2 + 2ax + a^2\]So yes a=2, but the question does not ask for a, it asks for what you should add to
\[x^2 + 4x\]to make it a perfect square trinomial (i.e. the first expression^ stated)