Question

NEED HELP NOW!!!!!!!!Find the number that should be added to the expression to create a perfect square trinomial. x^2-8x-161664-64

Answer 1

From a perfect square trinomial

`a^2+2ab+b^2`

We know that:

`2ab=2\cdot\sqrt[]{a^2}\cdot\sqrt[]{b^2}`

Now, let's use this for the trinomial given:

`x^2-8x+b^2`

We know that:

`-8x=2\cdot x\cdot b^2`

Solving for b,

`\begin{gathered} -8x=2xb \\ \rightarrow b=-(8x)/(2x)\Rightarrow b=-4 \end{gathered}`

This way, the complete perfect square trinomial is:

`x^2-8x-16`

Ans: Option A