Условие:

1) 7х-7^(х-1) = 6;

2) 3^(2y-1) + 3^(2y-2) - 3^(2y-4) = 315;

3) 5^3х + 3* 5^(3х-2) = 140;

4) 2^(х + 1) + 3 * 2^(х-1) - 5 * 2^х + 6 = 0.