А)11
б)-1
в) 0
г) 1
................................................
6)√225:√6,25-√5,76•√729=
15:2,5-2,4•27=6-64,5=-58,8
3x-4y=10
x=4y-2 => 3(4y-2) - 4y=10 => y=2 => 4*2-2=6
Ответ: x=6, y=2
Х²+5х-14=0
D = 25- 4×(-14)=25 + 56 = 81 = 9²
x1 = (-5 + 9)÷2= 2
x2 = (-5-9)÷2= -7