If a number is added to its square, the result is 56. How do you find the number?
Let the number be
We now solve the equation:
Call the number
I normally use the quadratic formula:
It's not hard to remember, and it always works.
For this particular one, though, I will factorise instead. I need two numbers that multiply to give
If you expand that you will get back our quadratic.
The two 'roots' - the solutions of the quadratic - are the values of
Those roots are