Question

Tìm y: (y+1)+(y+4)+(y+7)+.....+(y+49)=442

Answer 1

(y+1)+(y+4)+...+(y+49)=442

(y+y+...+y)+(1+4+...+49)=442

17y+425=442

17y=442-425

17y=17

y=17/17

y=1

Vậy y=1

Answer 2

Theo đề ta có : ( 1 + 4 + 7 + 10 +.... + 49 ) + 17y = 442

415 + 17y = 442 .

17 y = 442 - 415

17y = 27