已知x+y=1,求证:x³+3xy+y³=1
4个回答
x³+3xy+y³
=(x+y)(x²-xy+y²)+3xy
=x²-xy+y²+3xy
=x²+2xy+y²
=(x+y)²
=1
相关问题
已知 x+y=1,求证:x³+3xy+³=1
已知x,y∈R,求证:x-xy+y≥x+y-1
已知x,y∈R,求证:x+y+1≥x+y+xy
已知x,y∈R,求证x2-xy+y2>=x+y-1
已知x,y∈R,求证:x^2+y^2≥xy+x+y-1
已知x.y∈R,求证x2+y2+1≥x+y+xy
x-y=1求证x³-3xy-y³=1
已知1/x-1/y=-3,则x+3xy-y/3x-2xy-3y=
已知1/x-1/y=2,求3x+5xy-3y/x-xy-y
(1)已知x、y都是正实数,求证:x3+y3≥x2y+xy2;