When the sum of \, 528 \, and three times a positive number is subtracted from the square of the number, the result is \, 120. find the number?

Let be the unknown number. So, three times that number means , and the square of the number is

We have to sum 528 and three times the number, so we have

Then, we have to subtract this number from , so we have

The result is 120, so the equation is

This is a quadratic equation, i.e. an equation like . These equation can be solved - assuming they have a solution - with the following formula

If you plug the values from your equation, you have

So, the two solutions would be

But we know that x is positive, so we only accept the solution

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