(1)(2x^2+x)-[4x^2-(3^2-x)],其中x= -1又3分之2 (2)若a+b=5,a^3+b^3=50,求a^2+b^2的值 (3)已知a-2b+3c=7,4a+3b-2c=3,求代数式5a+12b-13c的值 (4)已知3x^2-x=1,求代数式6x^3+7x^2-5x+2011的值 (5)若x:y:z=3:4:7,且2x-y+z=18,求x+2y-z的值

来源：学生作业帮助网编辑：六六作业网时间：2024/11/23 01:03:18

(1)(2x^2+x)-[4x^2-(3^2-x)],其中x=-1又3分之2(2)若a+b=5,a^3+b^3=50,求a^2+b^2的值(3)已知a-2b+3c=7,4a+3b-2c=3,求代数式5

(1)(2x^2+x)-[4x^2-(3^2-x)],其中x= -1又3分之2 (2)若a+b=5,a^3+b^3=50,求a^2+b^2的值 (3)已知a-2b+3c=7,4a+3b-2c=3,求代数式5a+12b-13c的值 (4)已知3x^2-x=1,求代数式6x^3+7x^2-5x+2011的值 (5)若x:y:z=3:4:7,且2x-y+z=18,求x+2y-z的值
(1)(2x^2+x)-[4x^2-(3^2-x)]=2x^2+x-4x^2+3^2-x=9-2x^2=9-50/9=31/9
(2)若a+b=5,a^3+b^3=50,求a^2+b^2的值
a^3+b^3=(a+b)(a^2-ab+b^2)=50=5(a^2+b^2-ab) , a^2+b^2=10+ab
2(a^2+b^2)=20+2ab -------(1)
(a+b)^2=a^2+b^2+2ab=25 , a^2+b^2=25-2ab-------(2)
(1)+(2)
a^2+b^2=45
(3)已知a-2b+3c=7,4a+3b-2c=3,
5a+12b-13c=(4a+3b-2c)+(a-2b+3c)+11b+12c=11b-14c+10=-25+10=-15
4a-8b+12c=28------(1)
4a+3b-2c=3---------(2)
(2)-(1)
11b-14c=-25
(4)已知3x^2-x=1,求代数式6x^3+7x^2-5x+2011的值
6x^3+7x^2-5x+2011=x(6x^2+7x-5)+2011=x[2(3x^2-x)+9x-5]+2011=9x^2-3x+2011
=2014
(5)若x:y:z=3:4:7,且2x-y+z=18,求x+2y-z的值
这题不会

*-----------------------------------------------*| 6 4 X | 8 X X | X X 5 || X X X | X X X | X 7 8 || X X X | X X X | X X X ||---------------+---------------+--------------- || X X X | X X X | 5 1 X || X X X | X 6 X | X X X || 8 X X | 3 5 X | 2 X X || x+2/x+1-x+3/x+2-x+4/x+3+x+5/x+4 x^5-x^4+x^3-x^2+x-1 求一个数独答案X X X 9 X X X 8 2 X 6 3 X X 1 4 X 99 X 8 X X X X X XX X X 6 7 X 3 X XX 4 6 X 5 X 2 9 XX X 7 X 2 3 X X XX X X X X X 7 X 17 X 4 3 X X 6 2 X6 3 X X X 7 X X X 填九宫格帮帮忙.x x 6 x x 7 x x 98 x x x 3 x 1 x x 9 x x 6 x 5 x 3 x x x 3 x x x x 1 8x x x 9 x 1 x x x2 1 x x x x 6 x x x 6 x 7 x 3 x x 1 x x 9 x 2 x x x 47 x x 8 x x 5 x x 七年级下册政治复习提纲(山东人民出版社)第五单元是青春的脚步青春的气息别弄错了啊!格式：X X X X X X X X X 1、X X X X X X X X X X.2、X X X X X X X X X.3、X X X X X X X X X X X. 一个“整式的乘法”的问题请先阅读下列解题过程,再仿做下面的问题.已知X*X + X - 1=0,求X*X*X + 2*X*X + 3的值.解X*X*X + 2X*X +3=X*X*X +X*X -X +X*X +X +3=X{X*X +X -1} +X*X +X -1 +4=0+0+4=4+ x + X*X + X*X*X=0.+ X*X + X*X*X 难倒爱因斯坦的九宫格X 7 X | X 8 1 | X X X |X X X | X 4 X | 7 5 9 |X X 5 | 7 X 9 | X 1 4 |5 X X | X X 8 | 3 9 X |3 9 6 | 4 X 7 | X X 2 |X 8 7 | 9 X X | X X X |4 X X | 6 X 5 | X X X | X X 4 | X X 1 |2 X X | X X X | X X X | X 3 X | X X X |X 6 如下9*9宫图如何填x x x 1 x x x 2 9x x 5 x x x x x 4x 6 8 x x x x x xx x x 7 x x 5 x xx 2 x x 6 x x 8 xx x 3 x x 9 x x xx x x x 5 x 1 6 x 4 x x x 3 x x x x 7 x x x x 2 x x x 1/(1-x)+1/(1+x)+2/(1+x*x)+4/(1+x*x*x*x)+8/(1-x*x*x*x*x*x*x*x)怎么做 [x^2+2x-8/x^3+2x^2+x]÷[(x-2/x)×(x+4/x+1)]化简[x^2+2x-8/x^3+2x^2+x]÷[(x-2/x)×(x+4/x+1)]化简解九宫格题目（X为未知数）9 X 2 X 7 X 8 X XX X 4 X X 9 X 6 X1 3 X 5 X X X X 24 X X 8 5 X X 1 XX 8 9 4 X 1 6 7 XX 1 X X 3 6 X X 88 X X X X 2 X 3 6X 5 X 6 X X 9 X XX X 7 X 4 X 2 X 1 计算:[(x^2 - 4)/(x^2 - x - 6) + (x+2)/(x-3)] / (x+1)/(x-3) a+x/x+1 ,x/x^2-2x-3 ,a/x^2+4x+3 (x-3/x-2)-(x-2/x-1)=(x-5/x4) -(x-4/x-3) (x-1)/(x+3x+2)+6/(2+x-x)-(10-x)/(4-x) lim(x+1)^x+1(x+3)^x+3/x^2x+4 x趋于无穷 x(x+1)+(x+2)+(x+3)+(x+4)+(x+5) = 27求x