Question

Помогите решить #819, дам 20 баллов

Answer 1

1)

начнем с нижней суммы

1+5/(1+х)=(1+х+5)/(1+х)=(6+х)/(1+х)

1+4/(6+х)/(1+х)=1+4(1+х)/(6+х)=(6+х+4+4х)/(6+х)=(5х+10)/(6+х)=5(х+2)/(6+х)

5 : 5(х+2)/(6+х)=2

(6+х)/(х+2)=2

6+х=2(х+2)

6+х-2х=4

-х=-2; х=2.

2)

3 - 2/(3+х)=(3(3+х)-2)/(3+х)=(9+3х-2)/(3+х)=(7+3х)/(3+х)

4 : (7+3х)/(3+х)=4(3+х)/(7+3х)=(12+4х)/(7+3х)

1 + (12+4х)/(7+3х)=(7+3х+12+4х)/(7+3х)=(7х+19)/(7+3х)

3 : (7х+19)/(7+3х)=1

3 * (7+3х)/(7х+19)=1

21+9х=7х+19

2х=19-21

2х=-2

х=-1.

Проверку сделала в обоих.