Question

(X+5)/(X+4) ＋(X+8)/(X+7 )=(X+7)/(X+6 )＋(X+6)/(X+5 )

Answer 1

(X+5)/(X+4) ＋(X+8)/(X+7 )=(X+7)/(X+6 )＋(X+6)/(X+5 )

移项得到 (X+5)/(X+4)-(X+6)/(X+5 )=（X+7)/(X+6 )-(X+8)/(X+7 )

两边分别通分得到 [(x+5)(x+5)-(x+6)(x+4)]/(x+4)(x+5)=[(x+7)(x+7)-(x+8)(x+6)]/(x+6)(x+7)

将分子的括号打开得到 1/(x+4)(x+5)=1/(x+6)(x+7)

得到 x^2+13x+42=x^2+9x+20

所以 4x=-22

x=-11/2