10-4(2x+5)=6y-13
4y-63=5(4x-2y)+2
4y-63-20x+10y-2=0
14y-65-20x=0
x=0.7y-3.25
3-8x-6y=0
3-8*(0.7y-3.25)-6y=0
3-5.6y+26-6y=0
29-11.6y=0
y=29/11.6y=2.пятых
14*2.5-65-20x=0
-30-20x=0
x=-30/20
x=-1.5
9-2ˣ=2³⁻ˣ
9-2ˣ=2³/2ˣ
9-2ˣ=8/2ˣ
9*2ˣ-(2ˣ)²-8=0 2ˣ=t
t²-9t+8=0
D=81-32=49 √D=7
t₁=(9+7)/2=8 2ˣ=8 x=3
t₂=(9+7)/2=1 2ˣ=1 x=0