Sub in -7 as x
-(-7)^2 + 8(-7)
= -49 -56
= -105
You do 28, which is the original cost, then you take that 15% off to do that you multiply 28×.15 and you get 4.2 and subtract that from original cost and you get 23.8 then to get the cost after tax you do 23.8×.0675 and you get 1.6 then you add that to 23.8 and get 25.4 dollars
In scientific form or standard form?
<span />
2x*(4x^2)*(2x^2+x+7)
8x^3*(2x^2+x+7)
16x^5+8x^4+56x^3
Hope this helps :)