Question

Tìm y:

(y + 3) + (y + 7) + (y + 11) + .......+ (y + 79) = 860

Answer 1

(y+3)+(y+7)+...+(y+79)=860

(y+...+y)+(3+7+...+79)=860(lưu ý: y có 20 số hạng)

20y+820=860

20y=860-820

20y=40

y=40/20

y=2

Chúc bạn học tốt!^_^

Answer 2

\(\left(y+3\right)+\left(y+7\right)+\left(y+11\right)+...+\left(y+79\right)=860\)

\(\left(y+y+...+y\right)+\left(3+7+9+...+79\right)=860\)

\(20y+820=860\)

\(20y=860-820\)

\(20y=40\)

\(y=40:20\)

\(y=2\)

Answer 3

y=2 nha