Tính: A= 6/7 + 1/7 x 2/7 + 1/7 x 5/7; B= 4/9 x 13/3 - 4/3 x 40/9; A= 7/19 x 8/11 + 7/19 x 3/11 + 12/19

Question

A= 6/7 + 1/7 x 2/7 + 1/7 x 5/7

B= 4/9 x 13/3 - 4/3 x 40/9

A= 7/19 x 8/11 + 7/19 x 3/11 + 12/19

Làm đủ các bước nha!

Answer 1

A= 6/7 + 1/7 x 2/7 + 1/7 x 5/7=6/7+2/49+5/49=6/7+(2/49+5/79)=6/7+7/49=42/49+7/49=49/49=1

B= 4/9 x 13/3 - 4/3 x 40/9=52/27-160/27=-108/27=-4

A= 7/19 x 8/11 + 7/19 x 3/11 + 12/19=(7/19 x 8/11 + 7/19 x 3/11)+12/19=7/19.(8/11+3/11)+12/19=7/19.11/11+12/19

   =7/19.1+12/19=7/19+12/19=19/19=1