Question

If the square of a positive number is decreased by five times the number the result is 36. Find the

number.

please draw out the formula along with answer. show all work

Answer 1

The answer is 4

Explanation:

If we let

x equal the number, then,

x 2 + 5 x = 36

The square is indicated with ^ 2 .If we add it to five times that number, or

5 ⋅ x = 5 x , then we get x 2 + 5 x = 36 .

This is a quadratic! We subtract 36 from both sides to get x

2 + 5 x − 36 = 0 .

Solving it, we get

( x − 4 ) ( x + 9 ) .

Remember, though! The number must be positive.

x > 0 .

Therefore the only possible answer is

x = 4 .

Yay!