7x+4x化简1.7x+4x 化简2.1.小明今年9岁,奶奶今年73岁.当奶奶的年龄是小明的五倍时,奶奶多少岁?3.小明买了2元和8角的两种邮票共24枚,一共用去30元,这两种邮票各买了多少枚?

*-----------------------------------------------*| 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 || 化简：[(x+2)/x-(x-1)/(x-2)]/[(x-4)/(x^2-4x+4)] [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 化简：x-2x+3x-4x+5x-.+2011x-2002x 化简:X-2X+3X-4X+5X-……+2001x-2002x (x/x-2)+(2/x*2+2x)-(x+6/x*2-4)化简,=x^2/x(x-2)+(2x-4)/x(x^2-4)-(x^2+6x)/x(x^2-4)=x^2/x(x-2)-(x+2)/x(x-2)=(x-2)(x+1)/x(x-2)=(x+1)/x 化简 [3x/(x+2)-x/(x=2)]÷x/(x^2-4)化简 [3x/(x+2)-x/(x-2)]÷x/(x^2-4 3x/(x-2)-x/(x+2)÷2x/(x-4)化简3x/（x-2）-x/(x+2)÷2x/(x²-4)化简 化简：3x(5x^2-2)-x^2(4x+3)+8(7x+1) （x+3)(x-7)-(x-4)(X-5)=10x+9 化简,求值 3x^2-7x^2+2x^2-4x-3x 化简 8x-［-3x-（2x-7x-5）+3］+4x化简 8x²-【-3x-(2x²-7x-5)+3】+4x化简 化简:(x-1)(x+2)(x-3)(x+4)+24 化简 (x+1)(x+2)(x+3)(x+4)-8 化简：[x+1 -(15/x-1)] * (x-4/x-1) 化简9x-{4x-[5x-(8x-2)]} 化简【x-4】-【x-24】