# Rational Expressions - 2

#### Jason

##### Well-known member
Find the lowest common denominator:

(c.) $$\displaystyle \dfrac{10x - 5}{(9x)(15 + x)(8 + x)} + \dfrac{x - 8}{(15 + x)^{3})(6x)}$$

A combo of the highest terms: $$\displaystyle (9x)(6x)(8 + x)(6 - x)(15 + x)^{3}$$

@MarkFL Looks right? How could we put in the single x expressions?

#### MarkFL

##### La Villa Strangiato
Math Helper
I would think of the first denominator as:

$$\displaystyle 3^2x(x+8)(x+15)$$

And the second denominator as:

$$\displaystyle 2\cdot3x(x+15)^3$$

And so the LCD is:

$$\displaystyle 2\cdot3^2x(x+8)(x+15)^3$$

#### Jason

##### Well-known member
I would think of the first denominator as:

$$\displaystyle 3^2x(x+8)(x+15)$$

And the second denominator as:

$$\displaystyle 2\cdot3x(x+15)^3$$

And so the LCD is:

$$\displaystyle 2\cdot3^2x(x+8)(x+15)^3$$
So basically the x term is $$\displaystyle 18x$$