Question

A square piece of paper has an area of x2 square units. A rectangular strip with a width of 2 units and a length of x units is cut off of the square piece of paper. The remaining piece of paper has an area of 120 square units.

Which equation can be used to solve for x, the side length of the original square?


x2 − 2x − 120 = 0

x2 + 2x − 120 = 0

x2 − 2x + 120 = 0

x2 + 2x + 120 = 0

Answer 1

the answer is x² - 2x - 120 = 0

Answer 2

Let

x--------> the length side of the original square paper

we know that

the area of the original square paper is equal to

`A1=x*x=x^(2) \ units^(2)`

the area of the remaining piece of paper is equal to

`A2=x^(2) -2x\\ A2=120\ units^(2) \\ so\\ x^(2) -2x=120\\ x^(2) -2x-120=0`

therefore

the answer is the option

x2 − 2x − 120 = 0