(x/4)^2+[(20-x)/4]^2=17怎么得到的下一步(x/4)²+[(20-x)/4]²+2(x/4) [(20-x)/4]=17+2(x/4) [(20-x)/4]

*-----------------------------------------------*| 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 || 通分:x+4/x^2-8x+15,x-5/x^2+x-12,x-3/x^2-x-20 (x/x-2-x/x+2)/4x/x-2 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+4x)^2-x^2-4x-20 3(x^4)^6-2(x^5×x^3)^3+x^11×x^13+x^20×x^3×x 15X(4X-8)-5X(2X+10)=6X(5X-20) X(X-4)^2 |-x+2|+|4+x| x^4-x^2 (x^2-4)x x+2/x+1-x+3/x+2-x+4/x+3+x+5/x+4 通分x+4/x*x+4x与x-5/x(x-5)-2(x-5) (x+3x+5x...+2009x)-(2x+4x+6x+...+2010x) x(x+2)(x-2)-4x^2+8x x^5-x^4+x^3-x^2+x-1 x^6-x^5+x^4-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