Đáp án:
$\text{a) 180.}$
$\text{b) 640.}$
Giải thích các bước giải:
$\text{a) 26 × 7 - 17 × 9 + 13 × 26 - 17 × 11.}$
$\text{= (26 × 7 + 13 × 26) - (17 × 9 + 17 × 11).}$
$\text{= 26 × (7 + 13) - 17 × (9 + 11).}$
$\text{= 26 × 20 - 17 × 20.}$
$\text{= (26 - 17) × 20.}$
$\text{= 9 × 20.}$
$\text{= 180.}$
$\text{b) 32 × 19 + 32.}$
$\text{= 32 × 19 + 32 × 1.}$
$\text{= 32 × (19 + 1).}$
$\text{= 32 × 20.}$
$\text{= 640.}$
