`6/13+6/30  + 14/26 +1/15`

`=6/13+3/15 +7/13+1/15`

`=(6/13+7/13)+(3/15+1/15)`

`=13/13+4/15`

`=1+4/15`

`=19/15`

Nhanh giúp iem

a, -49

b, 25

c, 40

d, -88

a) (-10)-21-18=-(10+21+18)=-49

b) 24-(-16)+(-15)=24+16-15=40-15=25

c) 49-[15+(-6)]=49-9=40

d) (-44)-[(-14)-30]=-44-(-44)=0

a, -49

b, 25

c, 40

d, -88

cứu mình với

15 : 6 = 2,5

30 : 8 = 3,75

91 : 28 = 3, 25

455 : 14 = 32,5

 chúc e học tốt

đặt tính cột dọc giùm mình nha

thanks

= 12377

bạn đủ 10 sp rồi đăng câu hỏi sp mk mk sp lại

=12377

Giúp mình với nhé

ta có: 4  = 2 x 2

          6  = 2 x 3

       ...... = ..........

        30  = 2 x 15

 Nhân vế với vế ta có: 4x6x8x...x30 = 2¹⁴x (2x3x4x...x15)

⇒ \(\dfrac{1}{4}\times\dfrac{2}{6}\times\dfrac{3}{8}\times...\times\dfrac{14}{30}\times\dfrac{15}{32}\)  =   \(\dfrac{2\times3\times...\times14\times15}{2^{14}\times\left(2\times3\times...\times14\times15\right)\times32}\)

⇒  \(\dfrac{1}{2^{14}\times2^5}\) = \(\dfrac{1}{2^{2x+1}}\) ⇒  2¹⁹ = 2^\(2x\)+1 

⇒ 19 = 2\(x\) + 1 ⇒ 2\(x\) = 18 \(\Rightarrow\) \(x\) = 9

Cháu cảm ơn cô

\(\frac{7}{8}\div\left(\frac{14}{3}+\frac{14}{4}\right)+\frac{10}{14}\)

\(=\frac{7}{8}\div\left(\frac{56}{12}+\frac{52}{12}\right)+\frac{10}{14}\)

\(=\frac{7}{8}\div\frac{108}{12}+\frac{10}{14}\)

\(=\frac{7}{8}\div9+\frac{5}{7}\)

\(=\frac{7}{8}\times\frac{1}{9}+\frac{5}{7}\)

\(=\frac{7}{72}+\frac{5}{7}\)

\(=\frac{49}{504}+\frac{360}{504}\)

\(=\frac{409}{504}\)

\(\frac{30}{42}\div\left(\frac{5}{7}-\frac{5}{21}\right)+\frac{6}{8}\)

\(=\frac{6}{7}\div\left(\frac{15}{21}-\frac{5}{21}\right)+\frac{3}{4}\)

\(=\frac{6}{7}\div\frac{10}{21}+\frac{3}{4}\)

\(=\frac{6}{7}\times\frac{21}{10}+\frac{3}{4}\)

\(=\frac{126}{70}+\frac{3}{4}\)

\(=\frac{504}{280}+\frac{210}{280}\)

\(=\frac{714}{280}\)

\(\left(6-\frac{14}{15}\right).\frac{50}{38}-\frac{8}{18}\)

\(=\left(\frac{90}{15}-\frac{14}{15}\right).\frac{25}{19}-\frac{4}{9}\)

\(=\frac{76}{15}.\frac{25}{19}-\frac{4}{9}\)

\(=\frac{76.25}{15.19}-\frac{4}{9}\)

\(=\frac{19.2.2.5.5}{3.5.19}-\frac{4}{9}\)

\(=\frac{20}{3}-\frac{4}{9}\)

\(=\frac{60}{9}-\frac{4}{9}\)

\(=\frac{56}{9}\)

\(\frac{4}{6}+\frac{5}{21}.\left(\frac{4}{5}-\frac{2}{6}\right)\)

\(=\frac{2}{3}+\frac{5}{21}.\left(\frac{24}{30}-\frac{10}{30}\right)\)

\(=\frac{2}{3}+\frac{5}{21}.\frac{14}{30}\)

\(=\frac{2}{3}+\frac{70}{630}\)

\(=\frac{420}{630}+\frac{70}{630}\)

\(=\frac{490}{630}\)

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

2 - 3 - 6 - 7 - 8 - 14 - 15 - 30 = \(-81\)

2 - 3 - 6 -7 - 8 -14 -15 - 30 = - 81

Hok tốt

nha bạn.

số 8 không thuộc 

quy luật: 2+1=3

               3*2=6

                6+1=7

               7*2=14

               14+1=15

15*2=30....