MATHS F.4......THX!!!

85.)
5^(2x-1)-24(5^(x-1)) = 5
5^(2x) - 24(5^x) = 25
5^2x - 24(5^x) - 25 = 0
(5^x - 25)(5^x + 1) = 0
5^x = 25 or 5^x = -1(rej.)
x = 2
86.)
4x^(2/3) - 3x^(1/3) - 1 = 0
[4x^(1/3)+1][x^(1/3)-1] = 0
x^(1/3) = -1/4 or x^(1/3) = 1
x = -1/64 or 1
87.)
(x^2 - 3x)^2 - 2x^2 + 6x + 1 = 0
(x^2 - 3x)^2 -2(x^2 - 3x) + 1 = 0
[(x^2 - 3x) - 1]^2 = 0
x^2 - 3x - 1 = 0
x = [3+/-√(9+4)]/2
x = (3+/-√13)/2
88.)
2^x - 2^(3-x) = 7
2^2x - 7(2^x) - 8 = 0
(2^x -8)(2^x + 1) = 0
2^x = 8 or 2^x = -1(rej.)
x = 3
90.)
[log(x-1)]^2 - 2log(x-1) - 8 = 0
[log(x-1)-4][log(x-1)+2] = 0
log(x-1) = 4 or log(x-1) = -2
x-1 = 10000 or x-1 = 1/100
x = 10001 or 101/100
91.)
[log_2 (2x-1)]^2 - 3log_2 (2x-1) + 2 = 0
[log_2 (2x-1) - 2][log_2 (2x-1) - 1] = 0
log_2 (2x-1) = 2 or 1
2x-1 = 4 or 2
2x = 5 or 3
x = 5/2 or 3/2
93.)
[log(x+2)]^2 - log(x+2) - 2 = 0
[log(x+2) - 2][log(x+2) + 1] = 0
log(x+2) = 2 or -1
x+2 = 100 or 1/10
x = 98 or -19/10
119.)
x^4 +5x^2 - 36 = 0
(x^2 + 9)(x^2 - 4) = 0
x^2 = -9(rej) or 4
x = 2 or -2
120.)
6-x^2-x^4 = 0
x^4 + x^2 - 6 = 0
(x^2 + 3)(x^2 - 2) = 0
x^2 = -3(rej.) or 2
x = √2 or -√2

is solve , not slove .