观察：-x,3x^2,-5x^3,7x^4,...,-37x^19,39x^20,第n个式子是?

*-----------------------------------------------*| 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 || 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 观察等式：4x²-5x-6=（x-2）（4x+3）,2x²+7x+6=（2x+3）（x+2）,分解因式：-5x+7x+6 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 观察下列单项式 2x^2 -3x^3 5x^4 -9x^5 17x^6 13x^7 第n个单项式是多少? 观察下列单项式 2x^2 -3x^3 5x^4 -9x^5 17x^6 13x^7 第n个单项式是多少? 观察一列单项式,1X,3X^2,5X^2,7X,9X^2,11X^2…第2013个单项式为 观察：-x,3x^2,-5x^3,7x^4,...,-37x^19,39x^20,第n个式子是? 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 x+2x+3x+4x+5x+6x+7x+8x+9x=9x-8x-7x-6x-5x-4x-3x-2x-x.x等于多少? 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 用递归法求y=x-(x*x*x/3!)+(x*x*x*x*x/5!)-(x*x*x*x*x*x*x/7!)+. 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 2x+3x+4x+5x+x+6x+7x=100 x+2/x+1-x+4/x+3=x+6/x+5-x+8/x+7 x=? 计算:[(x+2)/(x+3) - (x+1)/(x+2) + (x+4)/(x+5) - (x+3)/(x+4) / (x^2 + 7x + 13)/(x^2 + 8x + 15) [(x+2)/(x+3)-(x+1)/(x+2)+(x+4)/(x+5)-(x+3)/(x+4)]/[(x的平方+7x+13)/(x的平方+8x+15)] 观察下面三行单项式：x,2x^2,4x^3,8x^4,16x^5,32x^6,…（1） - -2x观察下面三行单项式：x,2x^2,4x^3,8x^4,16x^5,32x^6,…（1） --2x,4x^2,-8x^3,16x^4,-32x^5,64x^6,…（2）2x^2,-3x^3,5x^4,-9x^5,17x^6,-33x^7…（3）取每行的第1