已知x2y等于4k
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(1)4ab+8-2b2-9ab-6=-2b2-5ab+2(2)原式=3x2y-2x2y+6xy-3x2y+xy=-2x2y+7xy,当x=-1,y=-2时,原式=-2×(-1)2(-2)+7×(-1
y=k/x(1)y=2x+k(2)将y=-4代入(1)得x=-k/4将其代入(2)得-4=2*(-k/4)+k解得k=-8
因为A+B+C=x3-2y3+3x2y+xy2-3xy+4+y3-x3-4x2y-3xy-3xy2+3+y3+x2y+2xy2+6xy-6=1,所以,对于x、y、z的任何值A+B+C是常数.
原式=2x2y+2xy-3x2y-3xy-4x2y=-5x2y-xy当x=-2,y=12时,原式=-9.
∵x+y=6,xy=4,∴x2y+xy2=xy(x+y)=4×6=24.故答案为:24.
4x-k≤00
原式=(4x2y+5xy2+3x-2y+5)-2(2x2y-3xy2-2x+1)=4x2y+5xy2+3x-2y+5-4x2y+6xy2+4x-2=11xy2+7x-2y+3.
∵xy<0,由二次根式的有意义,得y>0,∴x<0,∴原式=x2y=-xy.
∵m、n互为相反数∴m+n=0∵|k|=4所以k=±43m+3n+k+5=3(m+n)+k+5=k+5当k=4时原式=9当k=-4时,原式=1
A+B+C=(x3+3x2y-5xy2+6y3-1)+(y3+2xy2+x2y-2x3+2)+(x3-4x2y+3xy2-7y3+1)=(1+1-2)x3+(3+1-4)x2y+(-5+2+3)xy2
1.y=(kx+2k-4)/(k-1)得(k-1)y=kx+2k-4即:k(y-x-2)=y-4令y-x-2=y-4=0,即x=2,y=4则直线必过(2,4)点即无论k取不等于1的任何实数此直线都经过
答案:2x^2y+2xy^2原式=4x2y-{x2y-[3xy2-2x2y+4xy2+x2y]}-5xy2=4x2y-{x2y-[7xy2-x2y]}-5xy2=4x2y-{x2y-7xy+x2y]}
x=±1,y=±3,z=±2xyzz>y则0>x>z>yx=-1,y=-3,z=-2,x2y-[4x2y-(xyz-x2z)-3x2z]-2xyx=x2y-4x2y+xyz-x2z+3x2z-2xyx
x的m+k+3n次方等于x的m次方×x的k次方×(x的n次方)³=9×4×2²=288
由题意得(x-2)平方+(y-2)平方+(x-y)平方=0,故x=y=2,故x平方y=8
5x2y+3x2y+(-4x2y)=(5+3-4)x2y=4x2y,故答案为:4x2y.
K=B
∵x+2y=5,xy=1,∴2x2y+4xy2=2xy(x+2y)=2×1×5=10,故答案为:10.