Posted by Kristen on Monday, February 4, 2013 at 7:44pm.
I have to solve each equation using a u substitution and need help understanding how to do this.
The first equation is:
1. x^2/32x^1/315=0
2. x+4=7 Squareroot x+4

College Algebra help!!!  Reiny, Monday, February 4, 2013 at 7:52pm
x^2/32x^1/315=0
(x^(1/3))^2  2x^(1/3)  15 = 0
suppose we let x^(1/3) = y, then we get
y^2  2y  15 = 0
(y5)(x+3) = 0
y = 5 or y = 3
then x^(1/3)= 5 , cube both sides
x = 125
or
x^(1/3) = 3
x = 27
2.
x+4 = 7√(x+4)
square both sides
x^2 + 8x + 16 = 49(x+4)
x^2 + 8x + 16 = 49x +196
x^2  41x  180=0
(x45)(x+4) = 0
x = 45 or x = 4
BUT, since we squared, we must verify all answers
if x = 45
LS = 45+4 = 49
RS = 7√49 = 49 , works
if x = 4
LS = 0
RS = 7√0 = 0 , works
so x = 45 or x = 4

College Algebra help!!!  Kristen, Monday, February 4, 2013 at 8:03pm
Thank you so much this makes the examples provided make much more scense the way you broke them down! Thanks!
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