SOLUTION: Help with this one please! sqrt2y+7 + 4 = y I think I have to start by isolating the y to one side - is that right, and then do I subtract the 4 from both sides to cancel it

Question 39964: Help with this one please!
sqrt2y+7 + 4 = y
I think I have to start by isolating the y to one side - is that right, and then do I subtract the 4 from both sides to cancel it out on the left?
Please show me how to figure this!

Found 2 solutions by stanbon, Earlsdon:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
sqrt(2y+7) + 4 = y
sqrt(2y+7)=y-4
Square both sides to get:
2y+7=y^2-8y+16
y^2-10y+9=0
(y-9(y-1)=0
y=9 or y=1
Check the answers in the original equation.
y=1 is extraneous.
Cheers,
Stan H.

Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
You are correct...you have to get the variable y onto one side of the equation.
But you should use parentheses to clarify the problem;
Is it sqrt(2y+7) + 4 = y ?
or is it sqrt(2y) + 7 + 4 = y ?
or perhaps sqrt(2y+ 7 + 4) = y ?
I am going to assume that it's:
Subtract 4 from both sides of the equation.
Now square both sides.
Simplify.
Subtract 2y from both sides.
Now subtract 7 from both sides.
Solve by factoring.
Apply the zero products principle.
and/or
If , then
If , then
Now if youcheck these solutions by substituting y=1 and then y=9 into your original equation, you will find that y=9 works if you use only the positive value of and y=1 works if you use only the negative value of .
Try y = 3.

Only the positive value of works.
Try y = 1.

Only the negative value of works.

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