1)
x^2+2x-80=0
D=(2)^2-4*1*(-80)=4+320=324
x1=(-2+sqrt(324))/2=8
x2=(-2-sqrt(324))/2=-10
2)
15y^2-22y-37=
D=484+60*37=2704
y1=(22+52)/30=37/15
y2=(22-52)/30=-1
1)80³-50³=(8*10)³-(5*10)³=10³(8³-5³)=1000(8-5)(8²+8*5+5²)=<span><span>300*10(8²+8*5+5²)
</span> 2)87</span><span>³+32</span>³=(87+32)(87²-87*32+32²)=119(87²-87*32+32²)
3)75³+65³=(5*15)<span>³+(5*13)</span>³=5³(15³+13³)=5*25(15+13)(15²-15*13+13²)=
5*25*28(15²-15*13+13²)=700*5<span><span>(15²-15*13+13²)
</span>4)84³+24³ =.(12*7)³+(12*2)³=12³(7³+2³)=2³6³(7+2)(7²-7*2+2²)=8*216*9</span><span>(7²-7*2+2²)=</span>8*1944<span>(7²-7*2+2²)</span>
15x-x=2x-60, 15x-x-2x=60, 12x=60, x=5
Ответ:5
Объяснение:m^6=(m^3)^2, след. 6^2-31=36-31=5