Question

[scorpio girl lovely optimistic]

Bài 1 thực hiện phép tính 

a, \(\frac{16x17-5}{16x16+11}\)

b, 4/3x7 + 5/7x12 + 1/ 12 x 13 + 7/13x20 + 3/20x23

Answer 1

[What Coast]

\(\frac{16x17-5}{16x16+11}=\frac{16x16+16-5}{16x16+11}=1\)

\(\frac{4}{3x7}+\frac{5}{7x12}+\frac{1}{12x13}+....+\frac{3}{20x23}\)

=\(\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{12}+\frac{1}{12}-\frac{1}{13}+...+\frac{1}{20}-\frac{1}{23}\)

=\(\frac{1}{3}-\frac{1}{23}=\frac{20}{69}\)

Answer 2

[Dương Đức Hiệp]

a) \(\frac{16\cdot17-5}{16\cdot16+11}\)

= \(\frac{16\cdot16+16-5}{16\cdot16+11}\)

= \(\frac{16\cdot16+11}{16\cdot16+11}=1\)