View Full Version : Squaring both sides twice
wearepink
Dec 25, 2005, 05:51 PM
Here's a problem I am having troubles with.
_ ____
√x + √x – 5 = 5
Can someone help show me how to solve this?
Thanks,
B
CaptainForest
Dec 25, 2005, 11:37 PM
√x + √x – 5 = 5
Note that √x is also equal to x^1/2
Therefore,
√x + √x – 5 = 5
√x + √x = 5 + 5
2 √x = 10
√x = 10 / 2
√x = 5
x = 5^2/1
x = 25
Therefore, x=25
And a check,
√x + √x – 5 = 5
√25 + √25 – 5 = 5
5 + 5 - 5 = 5... Yes
Therefore, x=25
wearepink
Dec 29, 2005, 07:06 AM
Thanks for your help. When I posted my initial message it didn't post right. I am working on quadratic equations so I should wind up with x = ? Two times. The equation should be:
._.. . _____.
√x + √x – 5 = 5
Where the x - 5, not just the x, is under the square root symbol.
Thanks,
B
reinsuranc
Jan 5, 2006, 12:17 AM
It is easier to write such equations on this board as x^.5 + (x-5)^.5 = 5, instead of trying to draw square root symbols.
The answer to the above is 9:
x^.5 + (x-5)^.5 = 5
(x^.5 - 5)^2 = ( (x-5)^.5 )^2
x - 10x^.5 + 25 = x - 5
Let y = x^.5
y^2 - 10y + 25 = y^2 - 5
30 = 10y
y = 3
3 = x^.5
9 = x