math
posted by PLZ HELP ME NOW... .
the volume of a rectangular solid is given by expressions given below.in each case find the dimentions of the solid.
a)15x^251x+18.
b)x^3+13x^2+32x+20.
c)x^25x/23/2.
d)x^4+x^3x1
plz everyone help me out.till 2 o'clock...plz plz plz

Factorize:
a)15x^251x+18.
=15x^245x 6x+18
=15x(x3)  6(x3)
=(15x6)(x3)
b) x^3+13x^2+32x+20.
Notice that by changing the sign of odd powers, the coefficients add up to zero:
1+1332+20=0
So x+1 is a factor.
Divide by x+1 gives
x^2+12x+20
which factorizes readily to
(x+2)(x+10)
So the whole factorization is:
(x+1)(x+2)(x+10)
(c) x^25x/23/2.
=(1/2)(2x^25x3)
=(1/2)[2x^2+x  3(2x+1)]
=(1/2)[x(2x+1)3(2x+1)]
=(1/2)(x3)(2x+1)
(d) will be left as a practice for you.