Question

Factorize: 

y² + y – 72

Answer 1

Given, 

y² + y – 72 

Now, first we have to find out the numbers whose

Sum = 1 and 

Product = - 72 

The numbers are 9 and 8, 

So, 

y² + y – 72 

= y² + 9y – 9y – 72 

= y(y + 9) – 9(y + 9) 

= (y + 9)(y – 9)