Question

If 18 is subtracted from twice the square of an integer, the result is equal to nine times the integer. What is the value of the integer?

Answer 1

6 or -1.5

Explanation:

We can let this integer be x.

Therefore, according to the question we have:

`2x^2-18=9x`

Subtracting 9x, we have a quadratic:

`2x^2-9x-18=0`

Plugging into the quadratic equation:

`(9+√(81+144))/(4), (9-√(81+144))/(4),`

the square root of 81+144 is 15, so the answer is either 6 or -1.5