SOLUTION: HI COULD YOU PLEASE EXPLAIN THE ANSWER. SQUARE ROOT OF (Z+5)= 2Z

Question 597446: HI COULD YOU PLEASE EXPLAIN THE ANSWER.
SQUARE ROOT OF (Z+5)= 2Z
Found 3 solutions by stanbon, edjones, unlockmath:
Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
SQUARE ROOT OF (Z+5)= 2Z
----
Square both sides to get:
(z+5) = 4Z^2
---
Rearrange:
4z^2 - z + 5 = 0
---
z = [1 +- sqrt(1-4*4*5)]/8
----
z = [1 +- sqrt(-79)]/8
----
z = [1 +- isqrt(79)]/8
========================
cheers,
Stan H.
Answer by edjones(8007)   (Show Source): You can put this solution on YOUR website!
sqrt(z+5)= 2z
z+5=4z^2 square each side.
4z^2-z-5=0
4*-5=-20. the factors of -20 whose sum is -1 are -5 and 4
4z^2+4z-5z-5=0
4z(z+1)-5(z+1)=0
(4z-5)(z+1)=0
4z=5
z=5/4 This is the only answer.
.
Ed
Answer by unlockmath(1688)   (Show Source): You can put this solution on YOUR website!
Hello,
This SQUARE ROOT OF (Z+5)= 2Z is solved by squaring both sides to get:
Z+5= (2Z)^2
Subtract Z and 5:
0=4z^2-z-5
Factor:
0=(4z-5)(z+1)
Solve for z
4z-5=0
z=5/4
and
z=-1
Now plug these answers into the original and see if they work. You'll find one of these answers don't work. I'll let you find out which one it is.
RJ
www.math-unlock.com
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