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\(a,\frac{3\times4\times7}{12\times8\times9}\)
\(=\frac{3\times4\times7}{3\times4\times8\times9}\)
\(=\frac{7}{72}\)
\(b,\frac{4\times5\times6}{12\times10\times8}\)
\(=\frac{4\times5\times3\times2}{4\times3\times5\times2\times8}\)
\(=\frac{1}{8}\)
\(c,\frac{5\times6\times7\times9}{12\times7\times27}\)
\(=\frac{5\times6\times7\times9}{6\times2\times7\times9\times3}\)
\(=\frac{5}{6}\)
\(d,\frac{5\times6\times7}{12\times14\times15}\)
\(=\frac{5\times6\times7}{6\times2\times7\times2\times5\times3}\)
\(=\frac{1}{12}\)
a) \(\frac{3\times4\times7}{12\times8\times9}=\frac{3\times4\times7}{3\times4\times8\times9}=\frac{7}{8\times9}=\frac{7}{72}\)
b) \(\frac{4\times5\times6}{12\times10\times8}=\frac{4\times5\times6}{6\times2\times2\times5\times4\times2}=\frac{1}{2\times2\times2}=\frac{1}{8}\)
c) \(\frac{5\times6\times7\times9}{12\times7\times27}=\frac{5\times6\times9}{12\times27}=\frac{5\times6\times9}{2\times6\times3\times9}=\frac{5}{2\times3}=\frac{5}{6}\)
d) \(\frac{5\times6\times7}{12\times14\times15}=\frac{5\times6\times7}{2\times6\times2\times7\times3\times5}=\frac{1}{2\times2\times3}=\frac{1}{12}\)
a) \(\frac{2\cdot3\cdot5}{70}=\frac{30}{70}=\frac{3}{7}\)
b) \(\frac{2\cdot6\cdot11}{33\cdot24}=\frac{2\cdot6\cdot11}{3\cdot11\cdot2\cdot2\cdot6}=\frac{1}{6}\)
c) \(\frac{21\cdot45}{9\cdot7\cdot5\cdot3}=\frac{3\cdot7\cdot5\cdot9}{9\cdot7\cdot5\cdot3}=1\)
Chúc bạn học tốt.
mình chắc chắn là 8 . mình đã thi violympic rồi nên ko thể sai
1 x 2 x 3 x 4 x 5 x 6 x 7 + 64 : 8
= 1 x 2 x 3 x 4 x 5 x 6 x 7 + 8
= 5048
đ/s : 5048
nhé !
Vì 1 x 2 x 3 x 4 x 5 x 6 x 7 có tận cùng là chữ số 0 và 64 : 8 = 8 nên dãy tính trên có tận cùng là chữ số 8.
\(\frac{4\times6\times7}{28\times16\times6}\)
\(=\frac{4\times6\times7}{4\times7\times16\times6}\)
\(=\frac{1}{16}\)
4 x 6 x 7 / 28 x 16 x 6
= 4 x 6 x 7 / 7 x 4 x 4 x 4 x 6
= 1 / 4 x 4
= 1 / 16
Tk mk nha
dau . la dau x
a/ 1.3.2.4.3.5.4.6.5.7/2.2.3.3.4.4.5.5.6.6=1.7/2.6=7/12
b/ ab.aba=abab
aba=abab:ab
aba=101
=>a=1 b=0
aabb : ab = 99 hay ab x 99 = aabb hay ab x100 – ab = aabb
Ta có phép tính
__ ab00
___ab___
aabb
b=0 hoặc b=5
Nếu b=0 thì a000 – a0 = aa00 (sai)
Nếu b=5 thì
__ a500
__a5___
aa55
a=4
c) thay a=7/6 b=6/5 thi 3 x a + 4 : b - 5/12=3.7/6+4.6/5-5/12=7/2+24/5-5/12=210/60+288/60-25/60=473/60
**** nha
\(\frac{1.3.2.4.3.5.4.6.5.7}{2.2.3.3.4.4.5.5.6.6}=\frac{\left(2.3.4.5.6\right).\left(3.4.5.7\right)}{\left(2.3.4.5.6\right).\left(2.3.4.5.6\right)}=\frac{7}{12}\)
1=3/3=4/4=5/5=...
=> 1+1/1*3=3/1*3=1/1
=> 1+1/2*4=4/2*4=1/2
=>...
Bieu thuc se con lai la 1*1/2*1/3*1/4*1/5
Vay A=1/120
a: \(\dfrac{18\text{x}5}{24\text{x}7\text{x}3}=\dfrac{18}{24}\text{x}\dfrac{5}{7\text{x}3}=\dfrac{3}{4}\text{x}\dfrac{5}{21}=\dfrac{15}{84}=\dfrac{5}{28}\)
b: \(\dfrac{12\text{x}7\text{x}4}{36\text{x}6}=\dfrac{12}{36}\text{x}\dfrac{4}{6}\text{x}7=\dfrac{1}{3}\text{x}\dfrac{2}{3}\text{x}7=\dfrac{14}{9}\)
c: \(\dfrac{42\text{x}35}{45\text{x}16\text{x}4}=\dfrac{35}{45}\text{x}\dfrac{42}{16\text{x}4}=\dfrac{7}{9}\text{x}\dfrac{42}{64}\)
\(=\dfrac{7}{9}\text{x}\dfrac{21}{32}=\dfrac{147}{288}=\dfrac{49}{96}\)
a) 3 x 6 x 5 / 6 x 4 x 7 x 3 =5 / 4 x 7 =5 / 28
b)12 x 7 x 2 x 2 / 12 x 3 x 3 x 2 = 7 x 2 / 3 x 3
=14 / 9
c) 42 x 35 / 45 x 16 x 4
= 2 x 3 x 7 x 7 x 5 / 3 x 3 x 5 x 16 x 2 x 2
= 7 x 7/ 3 x 16 x 2
= 49/ 96