
Parviz F. answered 03/20/14
Tutor
4.8
(4)
Mathematics professor at Community Colleges
You need to write the problem correctly.
If :
√( X +34) = X +4
X + 34 = X^2 + 8X + 16
X ^2 + 7X - 18 =0
( X + 9 ) ( X -2 ) =0
X = -9 X = 2
Test :
√( -9 + 34) = -9 +4
√25 ≠ -5 / Not acceptable
√( 2 + 34) = 2 +4
√36 = 6 = 6 / acceptiale
If :
√X + 34 = X + 4
√ X = X - 30
X = X^2 - 60X + 900
X^2 - 61X + 900 =0
( X -36) ( X - 25) =0
X = 36 X =25
Test:
√36 +34 = 36 +4
40 = 40 / acceptable
√25 + 34 ≠ 25 +4
39 ≠ 29
Always have to test the answer with radicals, because raising to the power can result in extra roots.