Answer:
The second and third line are wrong
Step-by-step explanation:
(4x³ +4x²-8x) -(8x²-16x+4)
= 4x³ +4x²-8x - 8x²+ 16x -4
= 4x³ +4x²- 8x²-8x+ 16x -4
= 4x³ -4x²+ 8x -4
In the second line:
it has to be +16x because - times - is +
it is like -1*(8x²-16x+4)
In the third line:
you can only add or subtract the xs with the same exponentation, so
4x²- 8x² and -8x+ 16x
4x²- 8x²= -4x² not +12x²
