Michael J. answered 05/10/15
Tutor
5
(5)
Effective High School STEM Tutor & CUNY Math Peer Leader
For the first one.
√(6x) + 7 = √(7x + 7) + 6
Subtract 7 on both sides of equation.
√(6x) = √(7x + 7) - 1
Square both sides of equation.
6x = (√(7x + 7) - 1)2
6x = 7x + 7 - 2√(7x + 7) + 1
6x = 7x + 8 - 2√(7x + 7)
Subtract 7x and subtract 8 on both sides of equation.
-x - 8 = - 2√(7x + 7)
Divide both sides of equation by -2.
(1/2)x + 4 = √(7x + 7)
Square both sides of equation.
((1/2)x + 4)2 = 7x + 7
(1/4)x2 + 4x + 16 = 7x + 7
Subtract 7x and subtract 7 on both sides of equation.
(1/4)x2 - 3x + 9 = 0
Multiply both sides of equation by 4 to get rid of any denominators.
x2 - 12x - 36 = 0
(x - 6)(x - 6) = 0
x = 6
Second problem
7√(x2 + 3x - 1) + 8 = 5
Subtract 8 on both sides of equation.
7√(x2 + 3x - 1) = -3
√(x2 + 3x - 1) = -3/7
Square both sides of equation.
x2 + 3x - 1 = 9 / 49
Multiply both sides of equation by 49.
49x2 + 147x - 49 = 9
Subtract 9 on both sides of equation.
49x2 + 147x - 58 = 0
Use the quadratic formula to solve for x. I will let you take it from here.