Can you combine \frac { 4x + 2} { 3x ^ { 2} - 6x - 24} + \frac { 9} { 3x ^ { 2} - 15x + 12}4x+23x26x24+93x215x+12 into a single term?

1 Answer

(4x^2+7x+16)/(3x^3-9x^2-18x+24)4x2+7x+163x39x218x+24

Explanation:

First things first, we need to create a common denominator. Let's factor everything first and see if anything divides out

(2(2x-1))/(3(x^2-2x-8)) + (3 xx 3)/(3(x^2-5x+4))2(2x1)3(x22x8)+3×33(x25x+4)

(2(2x-1))/(color(green)(3)color(green)((x-4))(x+2)) + (3 xx 3)/(color(green)(3)(x-1)color(green)((x-4)))2(2x1)3(x4)(x+2)+3×33(x1)(x4)

Nothing divides out, but it looks like the denominators are mostly the same, except that the right side doesn't have (x+2)(x+2), and the left side is missing (x-1)(x1). Let's multiply both sides by the term they're missing (remember, multiply both the numerator and denominator)

(x-1)/(x-1) xx (4x+2)/(3(x-4)(x+2)) + (9)/(3(x-1)(x-4)(x+2)) xx (x+2)/(x+2)x1x1×4x+23(x4)(x+2)+93(x1)(x4)(x+2)×x+2x+2

(4x^2-4x+2x-2)/(3(x-4)(x+2)(x-1)) + (9x+18)/(3(x-1)(x-4)(x+2))4x24x+2x23(x4)(x+2)(x1)+9x+183(x1)(x4)(x+2)

Now that the denominators match, let's combine the numerators:

(4x^2-2x-2+9x+18)/(3(x-4)(x+2)(x-1))4x22x2+9x+183(x4)(x+2)(x1)

That denominator could use some work...

3(x-4)(x+2)(x-1)3(x4)(x+2)(x1)

(3x-12)(x+2)(x-1)(3x12)(x+2)(x1)

(3x^2+6x-12x-24)(x-1)(3x2+6x12x24)(x1)

(3x^2-6x-24)(x-1)(3x26x24)(x1)

3x^3-3x^2-6x^2+6x-24x+243x33x26x2+6x24x+24

color(green)(3x^3-9x^2-18x+24)3x39x218x+24

Now we have

(4x^2+7x+16)/(color(green)(3x^3-9x^2-18x+24))4x2+7x+163x39x218x+24

I hope that helps!