Posted by **PLZ HELP ME NOW...** on Wednesday, May 30, 2012 at 6:03am.

the volume of a rectangular solid is given by expressions given below.in each case find the dimentions of the solid.

a)15x^2-51x+18.

b)x^3+13x^2+32x+20.

c)x^2-5x/2-3/2.

d)x^4+x^3-x-1

plz everyone help me out.till 2 o'clock...plz plz plz

- math -
**MathMate**, Wednesday, May 30, 2012 at 6:55am
Factorize:

a)15x^2-51x+18.

=15x^2-45x -6x+18

=15x(x-3) - 6(x-3)

=(15x-6)(x-3)

b) x^3+13x^2+32x+20.

Notice that by changing the sign of odd powers, the coefficients add up to zero:

-1+13-32+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^2-5x/2-3/2.

=(1/2)(2x^2-5x-3)

=(1/2)[2x^2+x - 3(2x+1)]

=(1/2)[x(2x+1)-3(2x+1)]

=(1/2)(x-3)(2x+1)

(d) will be left as a practice for you.

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