Answer:
a) -8x³+x²+6x
d) 16x²-9
Explanation:
a) -2x(x+4x²)+3(x²+2x)
Expand each bracket:
-2x(x+4x²)
As the -2x is on the outside of the bracket, you have to times everything inside the bracket by -2x.
-2x times x equals -2x²
-2x times 4x² equals -8x³
Then we expand the other bracket:
3(x²+2x)
3 times x² equals 3x²
3 times 2x equals 6x
We then put all of it together:
-2x²-8x³+3x²+6x
Collect like terms:
-8x³+x²+6x
b) (4x-3)(4x+3)
We will use the FOIL method:
F-First
O-outer
I-Inner
L-Last
Times the first two terms in each bracket:
4x times 4x equals 16x²
Times the outer terms in the bracket:
4x times 3 equals 12x
Times the inside terms in the bracket:
-3 times 4x equals -12x
Times the last terms in the bracket:
-3 times 3 equals -9
Put it together:
16x²+12x-12x-9
The 12x and -12x cancel out to leave 16x²-9
Hope this helps :)