Tìm x:
a, (1313+ 1616 ) .2x2x+ 2x+12x+1= 212212+210210
b, (1212- 1616) . 3x3x+ 3x+23x+2= 316316+313
1111+1212+1313+1414+1515+1616 / 2020+2121+2222+2323+2424+2525 =?
\(\frac{2323+1313+1414+1515+1616}{4141+2222+2323+2424+2525}\)
=\(\frac{8181}{13635}\)
11+22+33+44+55+66+77+88+99+1010+1111+1212+1313+1414+1515+1616+.........+20162016=?
> , < , =
1313/1717.... 13/17
161616/202020.... 5/6
1414/1818.....7/8
1212/1616..... 1515/2424
1313/1717=13/17
=>1313/17 = 13/17
161616/202020 =16/20=4/5=24/30 ;5/6=25/30
=>161616/202020 <5/6
so sánh :
\(\frac{111111}{666665}\)và\(\frac{1212+1313+1414+1515+1616}{1717+1818+1919+2020+2121}\)
Ai làm đúng và nhanh nhất mk k cho
cái thứ hai lớn hơn
Ta có : \(\frac{1212+1313+1414+1515+1616}{1717+1818+1919+2020+2121}=\frac{12+13+14+15+16}{17+18+19+20+21}=\frac{28\cdot\frac{5}{2}}{38\cdot\frac{5}{2}}=\frac{14}{19}\)
Dễ thấy \(\frac{111111}{666665}< \frac{1}{2}\) ( do 111111 < 666665/2 ) và \(\frac{14}{19}>\frac{1}{2}\) ( do 14 > 19/2 )
Vậy \(\frac{111111}{666665}< \frac{1212+1313+1414+1515+1616}{1717+1818+1919+2020+2121}\)
1313/1717 ..... 13/17 161616/202020 ....... 5/6
1414 ..... 7/8 1212/1616 ........1515/2424
1313/1717 = 13/17 161616/202020 < 5/6
1414 > 7/8 1212/1616 > 1515/2424
chúc bạn học tốt! ^_^
phần dưới cùng là cái underline đấy, ko phải dấu = đâu
Bài 5:
a,1111+1212+1313+1414+1515+1616/2020+2121+2222+2323+2424+2525
b,5.4:0,4x1420+4,5x780x3/3+6+9+12+.....+24+27
c,7,2:2x28,6+1,43x2x64/2+2+4+6+10+16+...110
1- 1212/1616
\(1-\dfrac{1212}{1616}\)
\(=1-\dfrac{3}{4}\)
\(=\dfrac{4}{4}-\dfrac{3}{4}\)
\(=\dfrac{1}{4}\)
1313 / 1616 + 3 / 5
\(\frac{1313}{1616}\)+ \(\frac{3}{5}\)
= \(\frac{13}{16}\)+ \(\frac{3}{5}\)
= \(\frac{65}{80}\)+ \(\frac{39}{80}\)
= \(\frac{104}{80}\)
= \(\frac{13}{10}\)
99/72 - 15/40 -1212/1616
\(=\dfrac{11}{8}-\dfrac{3}{8}-\dfrac{3}{4}=1-\dfrac{3}{4}=\dfrac{1}{4}\)