For this case we have the following expression:
[tex]x ^ 2 + 10x = 15[/tex]
Completing squares we have:
We divide the middle term by 2 and square it, this we will add to both sides of the equation:
[tex]x ^ 2 + 10x + (\frac {10} {2}) ^ 2 = 15 + (\frac {10} {2}) ^ 2\\x ^ 2 + 10x + (5) ^ 2 = 15 + 25\\(x + 5) ^ 2 = 40\\(x + 5) (x + 5) = 40[/tex]
Answer:
[tex](x + 5) (x + 5) = 40[/tex]
