Question 93423This question is from textbook
: sqrt (y) + sqrt (y+7) = 7 please help me solve for the unknown and show all work
This question is from textbook
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! sqrt (y) + sqrt (y+7) = 7
:
Subtract sqrt(y) from both sides:
sqrt(y+7) = 7 - sqrt(y)
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Square both sides, FOIL (7-sqrt(y))*(7-sqrt(y)), gets rid of radical on the left
y + 7 = 49 - 7*sqrt(y) - 7*sqrt(y) + y
y + 7 = 49 - 14*sqrt(y) + y
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Arrange everything on the left except the radical remains on the right:
y - y + 7 - 49 = 14*sqrt(y)
-42 = 14*sqrt(y)
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Square both sides, gets rid of the radical on the right, (square 14 also)
+1764 = 196y
:
y = 1764/196
:
y = 9
:
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Check solution in original equation:
sqrt (y) + sqrt (y+7) = 7
sqrt(9) + sqrt(9+7) = 7
sqrt(9) + sqrt(16) = 7
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Did this make sense to you?
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