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Answer:
[tex]4x^2-x+8[/tex]
Step-by-step explanation:
First expand [tex](x-8)^2[/tex].
[tex](x-8)(x-8)=x^2-16x+64[/tex]
Now Add:
[tex](x^2-16x+64)+(3x^2+15x-56)\\(x^2+3x^2)+(-16x+15x)+(64-56)=\\4x^2-x+8[/tex]
We want this:
3x^2 + 15x - 56 + (x - 8)^2
First, expand (x - 8)^2 using FOIL.
So, (x - 8)^2 = (x - 8)(x - 8).
(x - 8)(x - 8) = x^2 - 16x + 64.
We now add like terms.
3x^2 + 15x - 56 + x^2 - 16x + 64
4x^2 - x + 8
Done.