Question

Сократите дробь х^2+4/х^2-3х-28 и найдите её значение при х=-0,5

Answer 1

x² -3x -28 =(x -7)(x +4)

(x² +4x) /(x -7)(x +4) =x(x +4) /(x -7)(x +4) =x /(x -7) = -0.5/(-0.5 -7) = -1/2 : (-7.5) =1/2 : 75/10 =1/2 * 10/75 =10/75*2 =5/75 =1/15