Question #N378
The expression $90y^2 - 54y^2$ is equivalent to $ry(15y-9)$, where r is a constant. What is the value of r?
A. 2
B. 4
C. 6
D. 9
Correct Answer is: C
The expression $90y^2-54y^2$ can be simplified by factoring out a common factor of $18y^2$, giving us $18y^2(5-3)$. Since $ry(15y-9)$ is equivalent to $18y^2(5-3)$, it follows that $ry(15y-9)$ can be rewritten as $18y^2(5-3)$. We can see that the coefficient of y in the original expression is 90, while the coefficient of y in the simplified expression is 90. This means that the value of r must be 6. Therefore, the value of r is 6.