Giải bài 1 trang 162 - SGK Toán lớp 5

Hướng dẫn:

\(\underbrace{a + a + ...+a}_{n \, \text{số} \, \text{hạng}} = a . n\)

Bài giải:

a)

\(6,75 \text{kg} + 6,75 \text{kg} + 6,75 \text{kg} \\ = 6,75 \text{kg} \times (1 + 1 + 1) \\ = 6,75 \text{kg} \times 3 \\ = 20,25 \text{kg}\)

b)

\(7,14\text{m}^2 + 7,14\text{m}^2 + 7,14\text{m}^2 \times 3 \\ = 7,14\text{m}^2 \times (1 + 1 + 3) \\ = 7,14 \text{m}^2 \times 5 \\ = 35,7 \text{m}^2\)

c)

\(9,26 \text{dm}^3 \times 9 + 9,26 \text{dm}^3 \\ = 9,26 \text{dm}^3 \times (9 + 1) \\ = 9,26 \text{dm}^3 \times 10 \\ = 92,6 \text{dm}^3\)