已知,a等于2x的平方加上3x y减2x减一,b等于负x的平方加x2y减一,-搜答案-百度作业网

-12x^2-21x=-3(4x^2+7x)=-3*(4-2)=-3*2=-6

由x^2+x-1=0得x^2+x=1x^3+2x^2+3=x(x^2+x)+x^2+3=x+x^2+3=1+3=4

3x²-x=19x的4次方+12x³-2x²-7x+2011=3x²(3x²-x)+5x(3x²-x)+(3x²-x)-6x+20

x的平方减去2x加上y的平方减去6y加上10等于0就是x^2-2x+1+y^2-6y+9=0(x-1)^2+(y-3)^2=0x=1y=32x+3y=11

x^2+3x-1=0(x+3/2)^2-13/4=0(x+3/2+√13/2)(x+3/2-√13/2)=0x=-3/2-√13/2或x=√13/2-3/2

A=2x²+14x-1B=x²+7x-2A-2B=2x²+14x-1-2x²-147x+4=-1+4=3(3是常数,所以与x无关)

X平方减1分之2X减3等于X减1分之A加上X分之B应该是(2x-3)/(x^2-1)=A/(x-1)+B/(x+1)=[(A+B)x+(A-B)]/(x^2-1)可见A+B=2A-B=-3解得A=-1

题目给错了吧,应该为x的平方加上2x加上y的平方减去6y加上10等于0如果是,x^2+2x+y^2-6y+10=0,所以：(x+1)^2+(y-3)^2=0所以：x+1=0且y-3=0两式相加,得到：

x+y=4x-y=2√3x²+2xy+y²=(x+y)²=16x²-y²=(c+y)(x-y)=8√3

x²+x-1=0,x²+x=1x³+2x²+3=x³+x²+x²+3=x(x²+x)+x²+3=x×1+x&s

x^2+x+1=0x^3+2x^2+2x+3=(x^3+x^2+x)+(x^2+x+1)+2=0+0+2=2

由x²+2x-1=0两边同除x：x+2-1/x=0,∴x-1/x=-2,（x-1/x）²=（-2）²x²-2+1/x²=4,即x²+1/x&

a-2x+3=4x²-6x-2；a=4x²-4x-5;很高兴为您解答,skyhunter002为您答疑解惑如果本题有什么不明白可以追问,

x=√3-2x+2=√3两边平方x^2+4x+4=3x^2+4x=-1x^4+4x^3+2x^2+4x+4=x^2(x^2+4x)+2x^2+4x+4=x^2*(-1)+2x^2+4x+4=x^2+4

x3即2^2-2*2+3a>3得a>1,2^2为2的平方f(x)=x^2-2x+3a=(x-1)^2+3a-1在x>=2时是增函数所以a>1

(1)(x+y)^2=x^2+xy+xy+y^2=12+13=25(2)y^2-x^2=1,若x+y=5则y-x=0.2则x=2.6,y=2.4则x^2+y^2=12.52若x+y=-5则y-x=-0

x^2+x-1=0x^2=1-x是x^3+2x^2+1吧=x*x^2+2x^2+1=x[1-x]+2x^2+1=x-x^2+2x^2+1=x^2+x-1+2=0+2=2

x+1/x=3(x+1/x)^2=9x^2+1/x^2+2=9x^2+1/x^2=7x^2/(x^4+x^2+1)=1/(x^2+1/x^2+1)=1/(7+1)=1/8

x^2+2x-m+1=0没有实数根,所以：b^2-4ac=2^2+4(m-1)＜0,即m＜0x^2+mx+2x+2m+1=0x^2+(m+2)x+(2m+1)=0b^2-4ac=(m+2)^2-4(2

（3x+2)²=243x+2=±√243x+2=±2√63x=±2√6-2x=(±2√6-2)/3x1=(2√6-2)/3,x2=(-2√6-2)/3