Решение
1) 2^x = 5
log₂ (2^x) = log₂ 5
x = log₂ 5
2) 2^x - 1/4 = 0
2^x = 1/4
2^x = 2⁻²
x = - 2
B/(a + b) : (1/(a - b) + 1/(a + b)) = b/(a + b) :(a + b + a - b)/(a + b)(a - b) = b/(a + b) : 2a/(a + b)(a - b) = b/(a + b) * (a + b)(a - b)/2a = b(a - b)/2a
4.3*(-2.7 - 4.3)/-2.7*2 = 4.3*7/5.4 = 301/54 = 5 31/54
Ответ 2а в 10+6а в 2-3а +11
14+ х^2-14х+49=78
х^2-14х+14+49-78=0
х^2-14х-15=0
по т.Виета:
х1+х2=14
х1*х2=-15
х1=15
х2=-1
Ответ : 15; -1.