Question

The area of a rectangular room is 750 square feet. The width of the room is 5 feet less than the length of the room. Which equations can be used to solve for y, the length of the room? Select three options. y(y + 5) = 750 y2 – 5y = 750 750 – y(y – 5) = 0 y(y – 5) + 750 = 0 (y + 25)(y – 30) = 0

Answer 1

B, C, E

Explanation:

Let y = length.

Then, y - 5 = width.

area = length × width

area = y(y - 5)

area = 750

y(y - 5) = 750

y² - 5y = 750

A: y(y + 5) = 750

Since y = length, width must be y - 5, not y + 5, so A does not work.

B: y² - 5y = 750

This is what we got above, so this equation works.

C: 750 - y(y - 5) = 0

750 = y(y - 5)

750 = y² - 5y

This is the same as B and works.

D: y(y - 5) + 750 = 0

y(y - 5) = -750

The area cannot be -750, so this equation does not work.

E: (y + 25)(y - 30) = 0

y = -25 or y = 30

This also works.

Answer: B, C, E