Factor 5y^2-3y-14

Question

Following this method here https://www.youtube.com/watch?v=r1JAJfmRG5w

 

My equation now looks something like 

x^2 - 3x - 70

I know that I have to use a -10 and +7, but I don't know how to set up the rest.

Answer 1

5y² - 3y - 14

 

ay² - by - c                 a=5, b= 3, c= 14

 

find a*c

5*14= 70

 

Find factors of 70 that add to -3.             -10, 7

 

5y² - 3y - 14 = 5y² -10y + 7y - 14

 

Factor out 5y and 7 because they are common factors in 5y² - 10y and 7y-14

 

5y(y - 2) + 7(y-2)

 

y-2 is a common factor. Treat is as 'x'.

 

5yx + 7x = 5y(y-2) + 7(y-2)

 

Factor out x

 

x(5y + 7)

 

Put in y-2 for x

 

(y - 2)(5y + 7)

 

Yay!