SOLUTION: sqrt2y+7 + 4 = y The sqrt is 2y+7 I am not sure how to work this problem since the equal number is a letter. How would I go about figuring out this equation?

Algebra ->  Radicals -> SOLUTION: sqrt2y+7 + 4 = y The sqrt is 2y+7 I am not sure how to work this problem since the equal number is a letter. How would I go about figuring out this equation?      Log On


   

Question 65696: sqrt2y+7 + 4 = y
The sqrt is 2y+7
I am not sure how to work this problem since the equal number is a letter. How would I go about figuring out this equation?
Answer by funmath(2933) About Me  (Show Source):
You can put this solution on YOUR website!
sqrt2y+7 + 4 = y
sqrt%282y%2B7%29%2B4=y
sqrt%282y%2B7%29%2B4-4=y-4
sqrt%282y%2B7%29=y-4
%28sqrt%282y%2B7%29%29%5E2=%28y-4%29%5E2
2y%2B7=y%5E2-8y%2B16
2y-2y%2B7-7=y%5E2-8y-2y%2B16-7
0=y%5E2-10y%2B9
0=(y-1)(y-9)
y-1=0 or y-9=0
y-1+1=0+1 or y-9+9=0+9
y=1 or y=9
Check for extraneous solutions:
for y=1
sqrt%282%281%29%2B7%29%2B4=1
sqrt%289%29%2B4=1
3%2B4=1
7=1 False, therefore y=1 is extraneous
For y=9
sqrt%282%289%29%2B7%29%2B4=9
sqrt%2818%2B7%29%2B4=9
sqrt%2825%29%2B4=9
5%2B4=9
9=9 True, y=9 is valid.
The only true solution is highlight%28y=9%29
Happy Calculating!!!