1)
7⁻²х = 21 + 3⁻¹,
1/49 х = 21 + 1/3,
1/49 х = 21 1/3,
х = 21 1/3 : 1/49,
х = 64/3 * 49,
х = 3136/3,
х = 1045 1/3,
2)
0,01 * 10³х + 5² - х = 2 * 5²,
0,01 * 1000х + 25 - х = 2 * 25,
10х - х = 50 - 25,
9х = 25,
х = 2 7/9,
3)
(3 * 3⁻²)*х / 6⁻² = 2² * 3,
(3 * 1/9)*х / (1/36) = 4 * 3,
(1/3 х) / (1/36) = 12,
1/3 х * 36 = 12,
12х = 12,
х = 1,
4)
(5³ * 3³)*х / (12⁰ * 15³ * 2) = 10⁻¹,
(125 * 9)*х / (1 * 3375 * 2) = 1/10,
1125 х : 6750 = 1/10,
1125 х * 1/6750 = 1/10,
1/6 х = 1/10,
х = 1/10 : 1/6,
х = 1/10 * 6,
х = 3/5 (или 0,6)