Multiply and divide as indicated.

[tex]\[ \frac{x^2 + x - 12}{x^2 + x - 72} \cdot \frac{x^2 + 7x + 12}{x^2 - x - 6} \div \frac{x + 4}{x^2 + 11x + 18} \][/tex]



Answer :

Sure! Let's solve the given expression step by step:

The given expression is:
[tex]\[ \frac{x^2 + x - 12}{x^2 + x - 72} \cdot \frac{x^2 + 7x + 12}{x^2 - x - 6} \div \frac{x + 4}{x^2 + 11x + 18} \][/tex]

### Step 1: Factor all the polynomials

First, factor each polynomial where possible.

#### Numerators:

1. [tex]\( x^2 + x - 12 \)[/tex]
- This can be factored as [tex]\((x + 4)(x - 3)\)[/tex].

2. [tex]\( x^2 + 7x + 12 \)[/tex]
- This can be factored as [tex]\((x + 3)(x + 4)\)[/tex].

3. [tex]\( x + 4 \)[/tex]
- This is already a simplest form.

#### Denominators:

1. [tex]\( x^2 + x - 72 \)[/tex]
- This can be factored as [tex]\((x + 9)(x - 8)\)[/tex].

2. [tex]\( x^2 - x - 6 \)[/tex]
- This can be factored as [tex]\((x - 3)(x + 2)\)[/tex].

3. [tex]\( x^2 + 11x + 18 \)[/tex]
- This can be factored as [tex]\((x + 9)(x + 2)\)[/tex].

### Step 2: Substitute the factored forms

The expression now looks like:

[tex]\[ \frac{(x + 4)(x - 3)}{(x + 9)(x - 8)} \cdot \frac{(x + 3)(x + 4)}{(x - 3)(x + 2)} \div \frac{x + 4}{(x + 9)(x + 2)} \][/tex]

### Step 3: Rewrite the division as multiplication by the reciprocal

[tex]\[ \frac{(x + 4)(x - 3)}{(x + 9)(x - 8)} \cdot \frac{(x + 3)(x + 4)}{(x - 3)(x + 2)} \cdot \frac{(x + 9)(x + 2)}{x + 4} \][/tex]

### Step 4: Simplify by canceling common factors

1. Cancel [tex]\((x - 3)\)[/tex] in the numerator and denominator:
[tex]\[ \frac{(x + 4)}{(x + 9)(x - 8)} \cdot \frac{(x + 3)(x + 4)}{(x + 2)} \cdot \frac{(x + 9)(x + 2)}{x + 4} \][/tex]

2. Cancel [tex]\((x + 4)\)[/tex] in the numerator and denominator:
[tex]\[ \frac{1}{(x + 9)(x - 8)} \cdot \frac{(x + 3)(x + 4)}{(x + 2)} \cdot \frac{(x + 9)(x + 2)}{1} \][/tex]

3. Cancel [tex]\((x + 2)\)[/tex] in the numerator and denominator:
[tex]\[ \frac{1}{(x + 9)(x - 8)} \cdot (x + 3)(x + 4) \cdot (x + 9) \][/tex]

4. Cancel [tex]\((x + 9)\)[/tex] in the numerator and denominator:
[tex]\[ \frac{1}{(x - 8)} \cdot (x + 3)(x + 4) \][/tex]

The remaining expression is:
[tex]\[ \frac{(x + 3)(x + 4)}{x - 8} \][/tex]

### Final Simplified Expression

[tex]\[ \frac{(x + 3)(x + 4)}{x - 8} \][/tex]

Thus, the simplified form of the given expression is:
[tex]\[ \boxed{\frac{(x + 3)(x + 4)}{x - 8}} \][/tex]