39/17

39/17

  12/17 + 19/17 + 8/17

=         31/17 + 8/17

=            39/17

Vậy.... [kết luận]

a) \(\dfrac{\dfrac{3}{14}-\dfrac{3}{17}+\dfrac{3}{19}}{\dfrac{5}{19}+\dfrac{5}{14}-\dfrac{5}{17}}=\dfrac{3\left(\dfrac{1}{14}-\dfrac{1}{17}+\dfrac{1}{19}\right)}{5\left(\dfrac{1}{14}-\dfrac{1}{17}+\dfrac{1}{19}\right)}=\dfrac{3}{5}\)

c) \(\dfrac{\dfrac{2}{7}+\dfrac{2}{5}+\dfrac{2}{17}-\dfrac{2}{193}}{\dfrac{3}{7}+\dfrac{3}{5}+\dfrac{3}{17}-\dfrac{3}{293}}=\dfrac{2\left(\dfrac{1}{7}+\dfrac{1}{5}+\dfrac{1}{17}-\dfrac{1}{193}\right)}{3\left(\dfrac{1}{7}+\dfrac{1}{5}+\dfrac{1}{17}-\dfrac{1}{193}\right)}=\dfrac{2}{3}\)

d) 

bn viết thế khó hiểu lắm

viết lại đi mik giải cho

\(A=\frac{17^{18}+1}{17^{19}+1}\)

\(\Leftrightarrow17A=\frac{17^{19}+17}{17^{19}+1}\)

\(\Leftrightarrow17A=\frac{17^{19}+1+16}{17^{19}+1}\)

\(\Leftrightarrow17A=\frac{17^{19}+1}{17^{19}+1}+\frac{16}{17^{19}+1}\)

\(\Leftrightarrow17A=1+\frac{16}{17^{19}+1}\)

\(B=\frac{17^{17}+1}{17^{18}+1}\)

\(\Leftrightarrow17B=\frac{17^{18}+17}{17^{18}+1}\)

\(\Leftrightarrow17B=\frac{17^{18}+1+16}{17^{18}+1}\)

\(\Leftrightarrow17B=\frac{17^{18}+1}{17^{18}+1}+\frac{16}{17^{18}+1}\)

\(\Leftrightarrow17B=1+\frac{16}{17^{18}+1}\)

Vì \(1+\frac{16}{17^{18}+1}>1+\frac{16}{17^{19}+1}\) nên 17B > 17A

Suy ra B > A

Rút gọn rồi tính:                                                                                                                                               \(a.\frac{16}{24}-\frac{1}{3}=\frac{2}{3}-\frac{1}{3}=\frac{1}{3}\)

\(b.\frac{4}{5}-\frac{12}{60}=\frac{4}{5}-\frac{1}{5}=\frac{3}{5}\)

Tính rồi rút gọn:

\(a.\frac{17}{6}-\frac{2}{6}=\frac{15}{6}\)

\(b.\frac{16}{15}-\frac{11}{15}=\frac{5}{15}=\frac{1}{3}\)

\(c.\frac{19}{12}-\frac{13}{12}=\frac{6}{12}=\frac{1}{2}\)

1a2/3-1/3=1/3            c4/5-1/5=3/5             tinh roi rut gon 17/6-2/6=15/6=5/2             16/15-11/15=5/15=1/3           19/12-13/12=6/12=1/2

chuc bn hoc tot

lớp 1 à cu

Ta có A=17^18+1/17^19+1 < 17^18+1+16/17^19+1+16 = 17^18+17/17^19+17 = 17(17^17+1/17^18+1)= B

Vậy A<B

\(A=\frac{17^{18}+1}{17^{19}+1}\)

Ta có :  \(17A=\frac{17(17^{18}+1)}{17^{19}+1}=\frac{17^{19}+17}{17^{19}+1}=\frac{17^{19}+1+16}{17^{19}+1}=1+\frac{17}{17^{19}+1}\)                    \((1)\)

\(B=\frac{17^{17}+1}{17^{18}+1}\)

Ta lại có : \(17B=\frac{17(17^{17}+1)}{17^{18}+1}=\frac{17^{18}+17}{17^{18}+1}=\frac{17^{18}+1+16}{17^{18}+1}=1+\frac{17}{17^{18}+1}\)        \((2)\)

Từ 1 và 2 suy ra : \(1+\frac{16}{17^{19}+1}< 1+\frac{16}{17^{18}+1}\)

Nên \(17A< 17B\)

Hay \(A< B\)

Vậy : \(A< B\)

ta có \(A=\frac{17^{18}+1}{17^{19}+1}< 1\)

\(A=\frac{17^{18}+1}{17^{19}+1}< \frac{17^{18}+1+6}{17^{19}+1+6}=\frac{17^{18}+17}{17^{19}+17}=\frac{17\left(17^{17}+1\right)}{17\left(17^{18}+1\right)}=B\)

\(< =>A< B\)

# T I C K MIK

a, 3/22 x 3/11 x 22

Cách 1

  3/22 x 3/11 x 22 = 9/242 x 22

                            = 198/242

                            = 9/11

Cách 2

3/22 x 3/11 x 22 = 3 x 3 x 22/22 x 11 x 1

                          = 9/11

b,( 1/2 + 1/3) x 2/5

Cách 1

( 1/2 + 1/3 ) x 2/5 = 5/6 x 2/5

                            = 10/30

                            = 1/3

Cách 2

( 1/2  +1/3) x 2/5 = 1/2 x 2/5 + 1/3 x 2/5

                           = 2/10  +  2/15

                           = 1/5  +  2/15

                           = 3/15  +  2/15

                           = 5/15

                           = 1/3

c, 3/5 x 17/21 + 17/21 x 2/5

Cách 1

3/5 x 17/21 + 17/21 x 2/5 = 51/105 + 34/105

                                        = 85/105

                                        =  17/21          

Cách 2

3/5 x 17/21 + 17/21 x 2/5 = 17/21 x (3/5 +2/5)

                                         = 17/21 x 5/5

                                         = 17/21 x 1

                                         = 17/21

 HỌC TỐT ( k mk nhé)