y=x^2-6x 13-x^2 4x 5

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已知x1,x2为方程x2+4x+2=0的两实根,则x13+14x2+55=______.

∵x1,x2为方程x2+4x+2=0的两实根,∴x12+4x1+2=0,x1+x2=-4,x1•x2=2,∴x12=-4x1-2,而x13=x12•x1,∴x13+14x2+55=x12•x1+14x

已知x1、x2为方程x2+5x+2=0的两实根,则x13+23x2+5=______.

∵x1、x2为方程x2+5x+2=0的两实根,∴x12=-(2+5x1),x1+x2=-5,∴x13+23x2+5=-(2+5x1)•x1+23x2+5=-2x1+5(2+5x1)+23x2+5=-2

2(x+y) 3x+3y=24 x+y/2x x y/2y= 1

由2(X+Y)3X+3Y=24得:2(X+Y)X+Y=8①;(X+Y/2X)XY/2Y=1得:X+Y=4②;由①、②得出Y=8(1-X),进入②知X=4/7;即Y=24/7

已知2/x+2/y=根号24,求 x/y(x-y) - y/x(x-y)的值

2/x+2/y=根号24(2y+2x)/xy=2√6x+y=xy√6x/y(x-y)-y/x(x-y)=1/(x-y)[(x/y-y/x)]=1/(x-y)[(x²-y²)/xy]

已知2/x 2/y=根号24,求 x/y(x-y) - y/x(x-y)的值

你的题目有点问题我这样做了x/{y(x-y)}-y/{x(x-y)}=(x平方-y平方)/{xy(x-y)}=(x+y)/xy2/x+2/y=2(x+y)/xy=根号24

6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5

设x-y=mx+y=n则6m-2n=143m+n=5解得m=2n=-1即x-y=2x+y=-1解得x=1/2y=-3/2

已知函数f(x)=x13−x−135,g(x)=x13+x−135.

(1)函数f(x)的定义域为{x|x≠0},则f(x)=(−x)13−(−x)−135=-x13−x−135=-f(x),∴函数f(x)是奇函数.当x>0时,函数y=x13为增函数,y=x−13为减函

x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20

由(1)得3x+3y+2x-2y=365x+y=36(3)由(2)得4x+4y-3x+3y=-20x+7y=-20(4)(3)×7-(4)得34x=272∴x=8把x=8代入(3)得y=-4∴x=8y

25x(13x4)=(25x4)x13

25x(13x4)=(25x4)x13运用了乘法交换律和乘法结合律.

设x1,x2是方程x2+x-1=0的两个实数根,那么x13-2x22+2008=______.

∵x1,x2是方程x2+x-1=0的两个实数根,∴x1+x2=-1;又∵x13=x1x12=x1(1-x1)=x1-x12=2x1-1-2x22=-2(1-x2)=-2+2x2,∴x13-2x22+2

{(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20

{(x+y)/2+(x-y)/3=63(x+y)+2(x-y)=36(1)4(x+y)-3(x-y)=-20(2)由(1)*3+(2)*2得9(x+y)+6(x-y)+8(x+y)-6(x-y)=36

分解因式:x15+x14+x13+…+x2+x+1.

∵x16-1=(x8)2-1=(x8+1)(x8-1)=(x8+1)[(x4)2-1]=(x8+1)(x4+1)(x4-1)=(x8+1)(x4+1)(x2+1)(x2-1)=(x8+1)(x4+1)

简算 6/5x13/1+9/5x13/2+18/5x13/6

5(6/5+9/5+18/5)+6(13/1+13/2+16/3)=6+9+18+6*13+3*13+2*16=182

4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6

第二个方程是不是写错了2/(x+y)+3/(x-y)=6是这样吗

(-5)x13分之3+(-5)x(-13分之2)-5x13分之1+0.125x(-13分之14)x(-8)的简便算法?

原式=(-5)×(13分之3-13分之2+13分之1)+13分之14=(-5)×13分之2+13分之2×7=13分之2×2=13分之4应该是这么做,

{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1

3(x+y)-4(x-y)=4(x+y)/2+(x-y)/6=1令a=x+y,b=x-y3a-4b=4(1)a/2+b/6=1则3a+b=6(2)(2)-(1)5b=2b=2/5a=(6-b)/3=2

若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于

若(x-y)/(x+y)=3那么x-y=3(x+y)x-y=3x+3y故x=-2y所以(x+2y)/(6x-7y)=(-2y+2y)/(6*(-2y)-7y)=0如果不懂,请Hi我,祝学习愉快!

0.8x+0.5x13=10.

0.8x+0.5x13=10.50.8x+6.5=10.50.8x=10.5-6.50.8x=4x=5