Question

[Nguyễn Quỳnh Trang]

Tính hợp lý:

a,  -3/4 + 3/7 + -1/4 + 4/9 + 4/7

b, -7/9 x 4/11 + -7/9 x 7/11 + 5 và 7/9 

c, ( 21/31 + 2013/6039 ) - ( 44/53 - 10/31) - /53

Answer 1

[võ ngọc mai]

a,  -3/4 + 3/7 + -1/4 + 4/9 + 4/7

=\(\left(\frac{-3}{4}+\frac{-1}{4}\right)+\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{4}{9}\)

=\(-1+1+\frac{4}{9}\)

=\(\frac{4}{9}\)

b, -7/9 x 4/11 + -7/9 x 7/11 + 5 và 7/9 

\(=\frac{7}{9}x\frac{-4}{11}+\frac{7}{9}x\frac{-7}{11}+5x\frac{7}{9}\)

\(=\frac{7}{9}x\left(\frac{-4}{11}+\frac{-7}{11}+5\right)\)

\(=\frac{7}{9}x4\)

\(=\frac{28}{9}\)

c, ( 21/31 + 2013/6039 ) - ( 44/53 - 10/31) - /53