Câu hỏi của Nguyen Ngoc Linh

Question

cho 8a+3b chia het 11.

cmr:2a+9b chia het 11

Hoàng Hà Nhi · Accepted Answer

Ta có: $8\left(2a+9b\right)-2\left(8a+3b\right)=\left(16a+72b\right)-\left(16a+6b\right)$

$=66b⋮11\Rightarrow8\left(2a+9b\right)-2\left(8a+3b\right)⋮11\left(1\right)$

$Do2a+3b⋮11\Rightarrow8\left(2a+3b\right)⋮11\left(2\right)$

Từ (1) và (2) ta suy ra $2\left(8a+3b\right)⋮11$$\Rightarrow2a+9b⋮11\left[Do\left(2;11\right)=1\right]$

Vậy $2a+9b⋮11$Câu trả lời: Ta có: $8\left(2a+9b\right)-2\left(8a+3b\right)=\left(16a+72b\right)-\left(16a+6b\right)$

$=66b⋮11\Rightarrow8\left(2a+9b\right)-2\left(8a+3b\right)⋮11\left(1\right)$

$Do2a+3b⋮11\Rightarrow8\left(2a+3b\right)⋮11\left(2\right)$

Từ (1) và (2) ta suy ra $2\left(8a+3b\right)⋮11$$\Rightarrow2a+9b⋮11\left[Do\left(2;11\right)=1\right]$

Vậy $2a+9b⋮11$