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b: =15/31(34/63-11/21)=15/31x1/63=5/651
a: \(=\dfrac{67}{63}\cdot5+\dfrac{11}{31}\cdot\dfrac{5}{7}=5\left(\dfrac{67}{63}+\dfrac{11}{31\cdot7}\right)=\dfrac{10880}{1953}\)
a)67/63 x 15/3 + 15/31 x 11/21
Thiếu đề
b)15/31 x 34/63 - 11/21 x 15/31
=15/31 x ( 34/63 -11/21)
= 15/31 x 1/63= 5/651
b: =15/31(34/63-11/21)=15/31x1/63=5/651
a: \(=\dfrac{67}{63}\cdot5+\dfrac{11}{31}\cdot\dfrac{5}{7}=5\left(\dfrac{67}{63}+\dfrac{11}{31\cdot7}\right)=\dfrac{10880}{1953}\)
b: =15/31(34/63-11/21)=15/31x1/63=5/651
a: =67/63⋅5+11/31⋅5/7=5(67/63+11/31⋅7)=10880/1953
\(\frac{2009\times2008-1}{2007\times2009+2008}\)
\(=\) \(\frac{4034071}{4034071}\)
\(=\) \(1\)
vì a3b chia hết cho 5 nên b = 0 hoặc 5
nếu b = 0 thì ( a +3+0 ) chia hết cho 3 hay a +3 chia hết cho 3
=> a =0 ; a = 3 ;a = 6 hoặc a=9
nếu b = 5 thì (a+3+5) chia het cho 3 hay a+ 8 chia het cho 3
=> a =1 ; a=4 hoặc a = 7
vay b =0 thì a=0
b=0 ; a=3
b=0 ;a=6
b=0 ;a=9
b=5 ; a=1
b=5 thi a =4
b=5 thi a =7
b sẽ phải bằng 0 vì trong dấu hiệu chia hết
a sẽ bằng số TN cộng với 3 phải bằng số chia hết số cho 3
A= 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 ..v.v
B= 0
\(x+\frac{5}{13}+\frac{10}{26}+\frac{15}{39}+\frac{20}{52}+\frac{401}{104}=\frac{25}{13}.\)
\(\Rightarrow x+\left(\frac{5}{13}+\frac{10}{26}+\frac{15}{39}+\frac{20}{52}+\frac{40}{104}\right)=\frac{25}{13}\)
\(\Rightarrow x+\frac{25}{13}=\frac{25}{13}\)
\(\Rightarrow x=\frac{25}{13}-\frac{25}{13}\)
\(\Rightarrow x=0\)
\(\leftrightarrow k-nha!!!!\)
\(x+\frac{5}{13}+\frac{10}{26}+\frac{15}{39}+\frac{20}{52}+\frac{40}{104}=\frac{25}{13}\) \(x+\left(\frac{5}{13}+\frac{10}{26}+\frac{15}{39}+\frac{20}{52}+\frac{40}{104}\right)=\frac{25}{13}\) \(x+\frac{25}{13}\) \(=\frac{25}{13}\) \(x\) \(=\frac{25}{13}-\frac{25}{13}\) \(x=0\)
\(\frac{1}{2}x+x-\frac{7}{2}x=21-\frac{1}{4}x\)
\(-2x=21-\frac{1}{4}x\)
\(-2x+\frac{1}{4}x=21\)
\(\frac{-7}{4}x=21\)
\(x=-12\)
a)C1:=2/7:2/5
=5/7
C2:=6/7:2/5-4/7:2/5
=15/7-10/7
=5/7
b)C1:=88/30+77/30
=11/2
C2:=(8/15+7/15):2/11
=1:2/11
=11/2
\(\dfrac{67}{63}\times\dfrac{15}{31}+\dfrac{15}{31}\times\dfrac{11}{21}\)
\(=\dfrac{15}{31}\times\left(\dfrac{67}{63}+\dfrac{11}{21}\right)\)
\(=\dfrac{15}{31}\times\left(\dfrac{67}{63}+\dfrac{33}{63}\right)=\dfrac{15}{31}\times\dfrac{100}{63}\)
\(=\dfrac{15}{63}\times\dfrac{100}{31}=\dfrac{5}{21}\times\dfrac{100}{31}=\dfrac{500}{651}\)
\(\frac{67}{63} \times \frac{15}{31} + \frac{15}{31} \times \frac{11}{21}\)
\(= \frac{15}{31} \times \left(\right. \frac{67}{63} + \frac{11}{21} \left.\right)\)
\(= \frac{15}{31} \times \left(\right. \frac{67}{63} + \frac{33}{63} \left.\right) = \frac{15}{31} \times \frac{100}{63}\)
\(= \frac{15}{63} \times \frac{100}{31} = \frac{5}{21} \times \frac{100}{31} = \frac{500}{651}\)