Answer
$4y+12$
Work Step by Step
Step by step multiplication of rational expressions:
1. Factor completely what you can
2. Reduce (divide) numerators and denominators by common factors.
3. Multiply the remaining factors in the numerators and
multiply the remaining factors in the denominators. $(\displaystyle \frac{P}{Q}\cdot\frac{R}{S}=\frac{PR}{QS})$
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Factor what we can:
$y^{2}-9=y^{2}-3^{2}=\qquad $... a difference of squares,
$=(y+3)(y-3)$
The problem becomes
$...=\displaystyle \frac{(y+3)(y-3)\cdot 4}{(y-3)}\qquad $... divide out the common factors
$=\displaystyle \frac{(y+3)\fbox{$(y-3)$}\cdot 4}{\fbox{$(y-3)$}}$
$=\displaystyle \frac{(y+3)\cdot 4}{1}$
= $4y+12$
