Multiply
1.
(x - 4)2
2.
(2y2 + 3)2
3.
(x - 7)(x + 7)
Factor:
4.
y2 - 9
5.
16k4 - 81
6.
2x2 - 6x
7.
4(x - y) - w(x - y)
8.
3 x + 3 z + a x + a z
9.
x2 a - b + b x2 - a
10. x3 - x
11.
3x2 - 10 xy - 8y2
12.
2y2 + yt - 6t2
13.
Solve H(a + b) = 2ab for a
14.
solve for f: d1
d2 = fd2 + fd1
15. Solve for r. 
16.
yx2 = 10 x
17.
x2 + 7x = -12
18.
8x2 = 3 - 10 x
19.
x3 - 4x2 = 21 x
20.
3x3 + x2 = 4(3x + 1)