What's "x squared minus 4x minus 45"

X^2 - 4x - 45 = 0

by using the ' splitting the middle term method ' ,

_ x _ = - 45 
_ + _ = - 4

the blanks ca be filled by using the digits ' -9 and 5 ' 

as -9 x 5 = - 45

and   -9 + 5 = - 4

therefore , 

x^2 - 9 x + 4x - 45 = 0 

taking the common factor out , 

x ( x-9 )    + 4 ( x - 9 ) = 0

therefore , 

a ) x - 9 = 0

and x = 9 

b ) x + 4 =0 

and x = -4