Question

please factor the ff:

1.x^2+16x-36
2.x^4-10x^2+9
3.(4+x)^2-(4+x)-20
4.2-3x^-1+x^-2 (all of the exponent here in number four is negative)

thanks.....

Answer 1

1. can you think of two numbers which when multiplies yields -36 and when added is 16
how about 18 and -2 ????
(x+18)(x-2)

2. can you think of two numbers which when multiplies yields 9 and when added is -10
how about -1 and -9
(x^2 - 1)(x^2 - 9)
now we have the difference of squares for both of them
= (x+1)(x-1)(x+3)(x-3)


3. for this one, let y = 4+x to get
y^2 - y - 20
which is easy ...
(y-5)(y+4), no replace y
= (4+x - 5)(4+x + 4)
= (x-1)(x+8

4.
rewrite it as
(1/x)^2 - 3(1/x) + 2
= (1/x -2)(1/x - 1)

Answer 2

thank you very much..:)