ksubtraction in algebra one with simplication

Question

(8+4x+7x to the second power + 8x to the third power) - (-9+4x- negative 7 to the second power + 8x to the third power)

Answer 1

(8+4x+7x²+8x³) - (-9+4x-7x²+8x³)

Distrubute - sign so that you can combine like terms

8+4x+7x²+8x³+9-4x+7x²-8x³

Combine like terms (I have my students put boxes around like terms with x³ including the signs in the front, put circles around x², put triangles around x, and under line plain numbers so the combining process is easier)

8+9, 4x-4x, 7x²+7x², 8x³-8x³

The answer is

17+14x²

Answer 2

Hi Dawn,

 

I think this is the problem?

 

(8 + 4x + 7x² + 8x³) - (-9 + 4x - 7x² + 8x³)

 

so we are subtracting all the terms within the second parenthesis from all those within the first

 

8 -(-9) + 4x -(4x)  + 7x² -(-7x²) + 8x³ - 8x³

 

and now lets simplify

 

17 + 14x²

 

Hope this helps