SOLUTION: Could you please help? I am having trouble understanding these problems. 1. The square root of y + 15 - the square root of y -15 = 1 solve for y. 2. -2 and the square root of -

Algebra ->  Square-cubic-other-roots -> SOLUTION: Could you please help? I am having trouble understanding these problems. 1. The square root of y + 15 - the square root of y -15 = 1 solve for y. 2. -2 and the square root of -      Log On


   

Question 587667: Could you please help? I am having trouble understanding these problems.
1. The square root of y + 15 - the square root of y -15 = 1 solve for y.
2. -2 and the square root of - 18.
3. 2 - the square root of 6 divided by -7
Found 2 solutions by htmentor, dfrazzetto:
Answer by htmentor(1343) About Me  (Show Source):
You can put this solution on YOUR website!
1. sqrt%28y%2B15%29-sqrt%28y-15%29=1
Squaring both sides gives y+%2B+15+%2B+y+-+15+-+2%2Asqrt%28%28y%2B15%29%28y-15%29%29+=+1
Simplifiy and isolate the square root on the LHS:
sqrt%28%28y%2B15%29%28y-15%29%29+=+y+-+1%2F2
Now square both sides again:
%28y%2B15%29%28y-15%29+=+y%5E2+-+y+%2B+1%2F4
y%5E2+-+225+=+y%5E2+-y+%2B+1%2F4
Simplify:
y = 225 1/4

Answer by dfrazzetto(283) About Me  (Show Source):
You can put this solution on YOUR website!
sqrt(y+15) - sqrt(y-15) = 1
sqrt(y+15) = sqrt(y-15) + 1
square both sides:
y+15 = y-15 + 2sqrt(y-15) + 1
29 = 2sqrt(y-15)
29/2 = sqrt(y-15)
square both sides:
841/4 = y-15
y = 841/4 + 15 = 841/4 + 60/4
y = 901/4 = 225.25