Question

Tormod bought a perfectly square table but found out it won't fit through his study
door. To solve the problem, he reduces its width by 9cm but also extends its length by
9cm. Its new area is 309cm?
What was the area of his original square table?

Answer 1

Answer:

390 cm^2

Step-by-step explanation:

Let's call the dimensions of the original square  x  by  x.  Its area is x^2.

After the table is altered, its dimensions are x + 9  by  x - 9, and you're given the area is 309 cm^2.

$(x+9)(x-9)=309\\\\x^2-81=309\\\\x^2=390$

This last equation is telling us the area of the original, square table.