could someone help me with math?

Question

could someone help me solve this?
Solve the equation.

y^2=5y+36

Answer 1

First, put the equation in standard form so you can factor it.

 

y² - 5y - 36 = 0

 

The pairs of factors that give you 36 are (1,36), (2,18), (3,12), (4,9), and (6,6). 

Your trailing coefficient is negative (-36) so one of the factors has to be negative. 

Further, the addition of the two factors has to be equal to -5, so it must be (4, -9)

 

(y - 9) (y + 4) = 0

 

So, the solutions are 9 and -4, because either of those numbers will turn one factor into 0 and the product of the two factors into 0.

 

You can double check your work either by substituting the two solutions into the original equation and demonstrating that the value of the function is 0 for those values x.  Or you can multiply your proposed factorization together  to verify that it does, in fact, equal the original equation.