r = -3,5
Объяснение:
2,6+12+(−1,22r)=5+2,6−3,22r
2,6+12−1,22r =5+2,6−3,22r
3,22r −1,22r =5+2,6−2,6-12
2r =5-12
2r =-7
r =-7/2
r =-3,5
Проверка
2,6+12+(−1,22*(-3,5)=5+2,6−3,22*(-3,5)
18,87 =18,87
