∫(9-1) [x^1 2-(x-3) 2]dx=?

|x-1|+|x-10|表示数轴上x到1的距离+x到10的距离.显然最小值是9,此时x只要在1到10之间就好.类似的,|x-2|+|x-9|的最小值是7,此时x在2到9之间就好.|x-3|+|x-8|

(1)x^2-4x+4/2x-4=(x-2)^2/2(x-2)=x-2/2(2)3x^2-9x-12/x^2+2x+1=3(x^2-3x-4)/(x+1)^2=3(x+1)(x-4)/(x+1)^2=

=x^18+x^15+x^12+x^9+x^6+x^3+1+x^3-1+5-4分解因式把下面的18换成21就是了=(x^18+1)+(x^15+1)+(x^12+1)+(x^9+1)+(x^6+1)+

1x+2x+3x+4x+5x+6x+7x+8x+9x+10x+11x+12x+13x+14x+15x=550120x=550x=55/12=4.583

(1/x^2+3x+2)+(1/x^2+5x+6)+(1/x^2+7x+12)+(1/x^2+9x+20)=1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)+1/(x+4)

中间错了原式=(x+2)/(x-3)(x+2)+2x/x(x-3)-(x+1)/(x-3)²=1/(x-3)+2/(x-3)-(x+1)/(x-3)²=3/(x-3)-(x+1)/

化简得2/x^2+6x=0,即（1+3x^3)/x^2=0,所以x=-（1/3)^(1/3)

原式=(x+2)/(x+2)(x-3)-2x/x(x-3)-(x+1)/(x-3)²=1/(x-3)-2/(x-3)-(x+1)/(x-3)²=-1/(x-3)-(x+1)/(x-

=9x^4+4(x+1)-3x^2-7x+1=9x^4-3x^2-3x+5=9x^4-3x(x+1)+5=9x^4-3x×3x^3+5=5

∫2^x*3^x/(9^x-4^x)dx=∫(2/3)^xdx/[1-(4/9)^x]=[ln(2/3)]^(-1)∫d[(2/3)^x]/{1-[(2/3)^x]^2}={[ln(2/3)]^(-1

原式=1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)+1/(x+4)(x+5)=1/(x+1)-1/(x+2)+1/(x+2)-1/(x+3)+1/(x+3)-1/(x+

应该是-2x²,不是-3x²3x²-x=1原式=9x^4-3x³+15x³-5x²+3x²-7x+2001=3x²(3x

【不好意思,题目太难让我想了很久】储备知识：x^n-y^n=(x-y)【x^(n-1)+x^(n-2)y+x^(n-3)y²+……+x²y^(n-3)+xy^(n-2)+y^(n-

1/(x^2+3x+2)+1/(x^2+5x+6)+1/(x^2+7x+12)+1/(x^2+9x+20)＝1/﹙x＋1﹚﹙x＋2﹚＋1/﹙x＋2﹚﹙x＋3﹚＋1/﹙x＋3﹚﹙x＋4﹚＋1/﹙x＋4﹚

变形为1/x-1/(x+1)+1/(x+1)-……+1/(x+9)-1/(x+10)=11/121/x-1/(x+10)=11/12x1=-5-1/11*4345^(1/2)x2=-5+1/11*43

136487259875239146942615837693572418584961372217348695468753921359126784721894563

分步写,好让看的清楚符号[√(x^2-6x+9)/x^2-x-12]=√(x-3)^2/(x-4)(x+3）=（x-3)/(x-4)(x+3）；(x^3-16x)/(x^2-3x)=x(x^2-16)

答：结论是无解的设1和4中间的正方形边长为x则左边中间的正方形边长为x+1左下角边长为x+1+x=2x+1所以：右下角正方形边长2x+1+x-4=3x-3所以：最大的正方形底部边长=2x+1+3x-3

1.9x-9/4-4x=9(x-1)/4(1-x)=-9/42.x^2-1/x^2+x-2=(x+1)(x-1)/(x-1)(x+2)=(x+1)/(x+2)3.x^2-4x+4/2x-4=(x-2)

1/x^2-3x+2-1/x^2-5x+6-1/x^2-7x+12-1/x^2-9x+20=1/(x-1)(x-2)-1/(x-2)(x-3)-1/(x-3)(x-4)-1/(x-4)(x-5)=1/