1) 6 1/4 * 8=25*8/4=25*2=50
ИЛИ 6 1/4 * 8=6*8 + (1/4)*8=48+2=50
2) 3 2/3 * 5=11/3 * 5=55/3=18 1/3
3) 2 2/5 * 4 7/12=12/5 * 55/12=(12*55)/(5*12)=сократим на 12 и 5=11
4) 50 - 18 1/3 +11=61 - 18 1/3=43 - 1/3=42 3/3 - 1/3=42 2/3.
4^2 = x^2 + 6x
x^2 + 6x - 16 = 0
D = 36 + 64 = 100
x1 = (-6 - 10)/2 = -8
x2 = (-6 + 10)/2 = 2
Проверка: log4(64-48) = log4(16)=2
log4(4+12) = log4(16) = 2
Ответ: -8 и 2