A₁ = - 79 a₂ = - 61
a₂ = a₁ + d
d = a₂ - a₁ = - 61 - (- 79) = - 61 + 79 = 18
8x=32 4x-y=20
x=4 4·4-y=20
16-y=20
y=-4
(2х-1)(х+1)=5
2х²+2x-x-1-5=0
2x²+x-6=0
D=1+48=49=7²
x(1)=(-1+7)/4=1.5
x(2)=(-1-7)/4= -2
1/(2(x+1))-1/(2x)≤1
1(2x+2)-1(2x)≤1
(2x-2x-2)/((2x+2)(2x)≤1
-2≤4x²+4x
4x²+4x+2≥0
((2x)²+4x+1)+1≥0
(2x+1)²+1≥0
x∈(-∞;+∞).