How do you solve 2z ( 2z + 11) = 42?

1 Answer
Nov 20, 2017

z = -7 and 3/2

Explanation:

2z (2z+11) = 42

4z^2 + 22z - 42 = 0

2(2z^2 + 11z - 21) = 0

2z^2 + 11z - 21 = 0

From here I'm going to split the middle term:

= 2z^2 - 3z + 14z - 21 = 0

= z (2z - 3) + 7 (2z - 3) = 0

= (z + 7) (2z - 3) = 0

=> z + 7 = 0 and 2z-3 = 0

=> z = -7 and 3/2

Or you could use quadratic formula!