15-5*X*2+(15-5*X)*2 = 45*X 我马上要开学了。还有一题：一个分数,分子比分母小1;如果分子减去2,分子只有分母的一半.这个分数是?

通分:x+4/x^2-8x+15,x-5/x^2+x-12,x-3/x^2-x-20 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)] 2x(x-1)-x(2x-5)=15 因式分解 (x+1)(x+2)(x+5)(x+7)+15 （x+1)(x+2)(x+5)(x+7)+15 因式分解 15X(4X-8)-5X(2X+10)=6X(5X-20) 解方程(x-3/x)-(3-x/x+1)=5x-15/2x+2 1x+2x+3x+4x+5x+6x+7x+8x+9x+10x+11x+12x+13x+14x+15x=550必须用解方程 *-----------------------------------------------*| 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 || .X²+13X+36 .X²+5X-20 .X²-2X-15 .8（X²+X）²-8（X²+X）+12 x(x*x-6x-9)-x(x*x-8x-15)+2x(3-x) x^2+8x+13/x^2+8x+15-x^2+5x+4/x^2+5x+62/x^2+4x+3+2/x^2+8x+15+2/x^2+12x+35 (2x^-5x+2/6x^+13x+6)*(6x^-5x-6/6x^-17x+10)*(12x^+8x-15/2x^-x)*(x/3-2x) 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 2x²-6x=5x-15(2x-1)(x+1)=(3x+1)(x+1) 求解2X*X-6X=5X-15在线等 还有是x*x-7x+12 matlab解决约束非线性规划问题myfun.mfunction f=myfun(x)f=x(1)*x(13)+x(2)*x(14)+x(3)*x(15)+x(25)+1.697*(x(4)*x(16)+...x(5)*x(17)+x(6)*x(18)+x(26))+0.575*(x(7)*x(19)+x(8)*x(20)...+x(9)*x(21)+x(27))+0.723*(x(10)*x(22)+x(11)*x(23)+x(12)*x(24));