Fill in the blank space
z2 + 5z – 36 = (z – 4)(z +_)

Answer=9

To solve this, we just have to find a number that, when added to -4, make a total of 5, and when multiplied by -4 make a total of -36.

x+-4=5

x*-4=-36

9 fits the parameters for both of these

9+-4=9
9-4=5
5=5

9*-4=36
36=36

Where’s the problems ? ?