b) 2^51 + 2^52 + 2^53 = x*2^50
2^50 (2 + 4 + 8) = x*2^50
2^50*14 = x*2^50
x = 14
d) 12*4^x - 5*4^x = 7*2^12
4^x (12 - 5) = 7*4^6
4^x*7 = 7*4^6
x = 6
f) 9^43 - 9^42 - 9^41 = 71*3^x
9^41 (81 - 9 - 1 ) = 71*3^x
9^41 *71 = 71*3^x
3^82 * 71 = 71*3^x
x = 82
h) 3 ^ x+3*4^x+1 - 5*3^x*4^x = 1236
3^x*4^x(27*4 - 5*1*1) = 1236
3^x*4^x*103 = 1236
3^x*4^x * 103 = 12 * 103
3^x*4^x = 12 = 3*4
x = 1
