a) 18/15 + 7/15 + 12/15 =18/15 + 12/15 + 7/15        

                                    = 30/15 + 7/15

                                     =       37/15

b) 9/7 + 8/7 +11/7 = 9/7 + 11/7 + 8/7 

                         =  20/7  + 8/7 =  28/7 nha . tk mk nhé b

a, 18/15+7/15+12/15= 37/15

b, 9/7+8/7+11/7=28/7=4

a ) \(\frac{18}{15}\)+ \(\frac{7}{15}\)+ \(\frac{12}{15}\)= \(\frac{37}{15}\)

b )\(\frac{9}{7}\)+ \(\frac{8}{7}\)+ \(\frac{11}{7}\)= 4

a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}\)

= \(\frac{18+7+12}{15}\)

= \(\frac{37}{15}\)

b) \(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}\)

= \(\frac{9+8+11}{7}\)

= \(\frac{28}{7}\)

a) 18/15 + 7/15 + 12/15

= (18/15 + 12/15) + 7/15

= 30/15 + 7/15

= 37/15

b) 9/7 + 8/7 + 11/7

= (9/7 + 11/7) + 8/7

= 20/7 + 8/7

= 28/7

chuc ban hok tot

a)18/15+7/15+12/15=(18/15+12/15)+7/15=30/15+7/15=37/15

b)9/7+8/7+11/7=(9/7+11/7)+8/7=20/7+8/7=28/7=4

đúng thì k cho mik nha

a,18/15+7/15+12/15=18+7+12/15

                             =37/15

b,9/7+8/7+11/7=9+8+11/7

                      =28/7=1/4

+8/15 + 7/15 +12/15 = (18+7+12)/7 = [(18+12)+7]/15= (30+7)/15=37/15=7/3

9/7 + 8/7 + 11/7 = (9+8+11)/7= [(9+11)+8]/7=(20+8)/7= 28/7 =4

a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}\)

\(=\left(\frac{18}{15}+\frac{12}{5}\right)+\frac{7}{15}\)

\(=6+\frac{7}{15}\)

\(=\frac{97}{15}\)

b) \(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}\)

\(=\frac{17}{7}+\frac{11}{7}\)

\(=\frac{28}{7}=4\)

TL

a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}\)\(=\frac{97}{15}\)

b) \(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}\)\(=4\)

nha bn

HT

 60x [7/12+4/15]

60x153/180

=9180/180

b 1/2x2/3x3/4x4/5x5/6x6/7x7/8x8/9=40320/4032

A = (2 + 2²) + (2³ + 2⁴ ) +…(2¹⁹⁹ + 2²⁰⁰)

A = 6 + 2² (2 + 2² ) +… + 2¹⁹⁸ (2 + 2²)

A = 6 + 2² (6 ) +… + 2¹⁹⁸ (6)

A = 6(1 + 2² +… + 2¹⁹⁸)

Vậy A chia hết cho 6

a) \(\left(\frac{2}{7}+\frac{3}{8}+\frac{12}{7}+\frac{5}{8}\right).\frac{19}{36}\)

\(=\left\{\left(\frac{2}{7}+\frac{12}{7}\right)+\left(\frac{3}{8}+\frac{5}{8}\right)\right\}.\frac{19}{36}\)

\(=\left(\frac{14}{7}+\frac{8}{8}\right).\frac{19}{36}\)

\(=\left(2+1\right).\frac{19}{36}\)

\(3.\frac{19}{36}=\frac{19}{12}\)

 a,  \(\dfrac{5\times11\times15\times18}{6\times15\times22\times10}\)

= \(\dfrac{5\times11\times15\times6\times3}{6\times15\times11\times2\times2\times5}\)

= \(\dfrac{5\times11\times15\times6}{5\times11\times15\times6}\) \(\times\) \(\dfrac{3}{2\times2}\)

= 1 \(\times\) \(\dfrac{3}{4}\)

= \(\dfrac{3}{4}\)

b, \(\dfrac{7}{12}\) \(\times\) \(\dfrac{3}{5}\) + \(\dfrac{3}{5}\) \(\times\) \(\dfrac{5}{12}\)

= \(\dfrac{3}{5}\) \(\times\) ( \(\dfrac{7}{12}+\dfrac{5}{12}\))

= \(\dfrac{3}{5}\) \(\times\) \(\dfrac{12}{12}\)

= \(\dfrac{3}{5}\) \(\times\) 1 

= \(\dfrac{3}{5}\)

Please