18X=19.8 7X的解-搜答案-智慧作业帮

(2x-3)(x-三分之一)=3x的平方-(x+1)(x-1)2x²-3x-2/3x+1=3x²-x²+111/3x=0x=0

设X²+3X为Y;Y-8=20/Y;Y²-8Y-20=0;(Y-10)(Y+2)=0;Y=10或-2;所以：1：X²+3X=10,X=2或-5;2:X²+3X=

x(x^2-2)+2x^2(x+3)-3x(5x-7)=x(3x^2-9x+17)+2=>x^3-2x+2x^3+6x^2-15x^2+21x=3x^3-9x^2+17x+2=>2x=2x=1

【解法一】【解法二】5x(x+7)(x+4)=5x(x^2+11X)5x(x²+11x+28)-5x(x²+11x)=05x^3+55x^2+140x=5x^3+55x^25x(x

(X-3)平方-(X+3)*(X-3)=(X+1)*(X+2)-(X-1)*(X+4)x^2-6x+9-x^2+9=x^2+3x+2-x^2-3x+4-6x+18=66x=18-66x=12x=2

提出x得到：x*(1-1/2+1/2-1/3+1/3-1/4……+1/2008-1/2009)=2008接着：x*(1-1/2009)=2008最后：x=2009

2x^2-5x-x^2-2x=x^2-6-7x=-6x=6/7

36x÷x=1836x=18x18x=0x=0经检验:x=0是原方程的增根.∴原方程无实数根.

x^4-4x^3-4x^2+15x+18=0x^4-3x^3-x^3+3x^2-7x^2+21x-6x+18=0(x-3)(x^3-x^2-7x-6)=0x1=3x2=3.49449283705542

x(x+3)-x(1-2x)=1+3x²x²+3x-x+2x²=1+3x²x²+3x-x+2x²-3x²=12x=1x=2分之1

设x1=4-√3,x2=4+√3,是方程X^2-8X+13=0的两根所以X1^2-8X1+15=2X^4-6X^3-2X^2+18X+23=(X+1)^2*(X^2-8X+13)+10=10所以原式=

./

当x＜0或者x＞2时,f（x）＝x³-2x²,f'(x)＝3x²-4x.当0＜x＜2时,f（x）＝2x²-x³,f'(x)＝4x-3x².当

（x+1)/(x+2)+(x+6)/(x+7)=(x+2)/(x+3)+(x+5)/(x+6)(x+2-1)/(x+2)+(x+7-1)/(x+7)=(x+3-1)/(x+3)+(x+6-1)/(x+

(x+x)+(x-x)+(xx)+(x/x)=1002x+0+x²+1=100x²+2x+1=100（x+1）²=10²x+1=10或x+1=-10x=9或x=

(x-3)(x+2)+18=x(x+1)x²-x-6+18=x²+xx+x=122x=12x=6

问题是不是X2=(X+30)*(X-18）啊?要是上面的话就这样X2=X*X-X*18+30*X-30*18=X2+12X-540移项得：X2-X2-12X=-540,即-12X=-540,X=45*

再答：望采纳，谢谢