(4.4x7.5x4.8)除以91.5x2.5x2.4）简便运算

(4.4x7.5x4.8)除以91.5x2.5x2.4）简便运算 x1-x2+x3=1x2-x3+x4=21若x1,x2,x3,x4,x5满足方程组 x3-x4+x5=3x4-x5+x1=4x5-x1+x2=5求x2 x3 x4的值2已知 x1+x4+x6+x7=39 x2+x4+x5+x7=49 x3+x5+x6+x7=41 x4+x7=13 x5+x7=14 x6+x7=9 x1+x2+x3+x4+x5+x6+x7=9求x7的值若x1,x2,x3,x4,x5满足方程组 x1-x 解方程 0.9x--4x1.3=1.1 1.3x7=25.1-8x 4.8+0.5x=6.3 （25+2x）x4=340 2.8x4-5x=5.8 x8+x7+x6 +x5+x4+x3+x2+x+1因式分解 x8+x7+x6+x5+x4+x3+x2+x+1因式分解 巧算：1x2+2x3+3x4+4x5+5x6+6x7...+8x9 简便计算：（9.1X4.8X7.5）/（0.25X1.3X1.6） 若X2+1除以X=5,求X4+X2+1除以X4-X2+1 若X2+1除以X=5,求X4+X2+1除以X4-X2+1 (1-1/2x4)x(1-3/3x5)x(1-5/4x6)x(1-7/5x7)x(1-9/6x8)x(1-11/7x9)x(1-13/8x10)x(1-15/9x11) 这几道题怎么简算?1.99.9X7+11.1X372.4.2X4.2+0.42X583.1.25X(8+0.8+0.8) 5分之3x4分之9x7分之5 简便运算.8.8x7.8+3.3x4.4 简便运算.8.8x7.8+3.3x4.4,急 (9.1 x 4.8x7.5)除以(0.25x1.3x1.6 )简算 1x2+2x3+3x4+4x5+5x6+6x7+7x8+8x9+9x10+10x11 1x2+2x3+3x4+4x5+5x6+6x7+7x8+8x9= 1/2x4+1/3x5+1/4x6+1/5x7+.1/8x10+1/9x11