3x2+2x2等于多少
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X1^2+3X1+1=0----3X1=-1-X1^2X2^2+3X2+1=02x1的二次方+x2的二次方+3x1=2X1^2+X2^2-1-X1^2=X1^2+X2^2-1=[x1+x2]^2-2x
令t=x-1/x,所以有f(t)=t平方+2,所以有f(3)=11
设(x²-1)/(x²+2x)=t则8t+3/t=118t²-11t+3=0(8t-3)(t-1)=0解得t=3/8或t=11.t=3/8(x²-1)/(x
根号3*根号3=33*2*2=12
用韦达定理.x1-x2=根号((x1+x2)^2-4x1x2),韦达定理代入相应数值即可
均是利用方程ax+bx+c=0两根之和等于-b/a,两根之积等于c/a来解题1.x1+x2=2,则x1+3x2=2+2x2=3,解出x2=0.5,代入原方程,解出m=0.75不懂还有追问!
(2x2-2/1+3x)-4(x-x2+2/1)=2x²-1/2+3x-4x+4x²-2=6x²-x-5/2
a=2,(a-1)x2+3x-2=0是一元二次方程△=3×3-4×(a-1)×2≥0得出a=1或a=2,(a-1)x2+3x-2=0是一元二次方程,a-1不等于0,所以a只能是2
=1/(x-2)(x-1)+1/(x-2)(x-3)+1/(x-3)(x-4)-4/(x-1)(x-5)帮你删除了1/x2-7=1/(x-2)-1/(x-1)+1/(x-3)-1/(x-2)+1/(x
1/1x2+1/2x3+1/3x4...+1/2006x2007=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+.+(1/2006-1/2007)=1
5x²-3x-5=0△=3²-4×5×(-5)=109x=[﹣(﹣3)±√109]/5由原方程可得所求式子=(x+5)-1/(x+5)所求式子=(118±6√109)/25-25/
依题意得,x2-2x-3=0且x2-1≠0,整理,得(x-3)(x+1)=0,且(x+1)(x-1)≠0.解得x=3.故选:C.
原式=5x²-x²-(4x-x²)+2(x²-3x)=4x²-4x+x²+2x²-6x=7x²-10x
x2/x1²+x1/x2²=(x1³+x2³)/x1²x2²=(x1+x2)(x1²-x1x2+x2²)/(x1x2)&
X1,X2为方程X^2+3X+1=0的两实根x1^2=-1-3x1x1+x2=-3x1*x2=1X1^3+8X2+20=x1(x1^2)+8x2+20=x1(-1-3x1)+8x2+20=-x1-3x
x^4+x^2和x^4-x^2,这两个是最终结果,没有同类项,不能再化简了x^4乘以x^2=x^(4+2)=x^6x^4除以x^2=x^(4-2)=x^2
1x2分之一+2x3分之一+3x4分之一+.+2010x2011分之一=1-1/2+1/2-1/3+1/3-1/4+……+1/2010-1/2011=1-1/2011=2010/2011
若x1>x2,则为x1-x2;若x1=x2,则为0;若x1
x1`x2是方程2x^+x-7=0的根那么x1+x2=-b/a=-1/2x1*x2=c/a=-7/2所以x1^2+x2^2=(x1+x2)^2-2x1*x2=1/4+7=29/4