Tinh gia tri bieu thuc
1+3+5+7+.....+35+37+39
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\(198,06-5,9\times6:\dfrac{3}{5}:\dfrac{5}{7}+\dfrac{3}{8}\)
\(=198,06-35,4:0,6:\dfrac{5}{7}+\dfrac{3}{8}\)
\(=198,06-59:\dfrac{5}{7}+\dfrac{3}{8}=198,06-82,6+0,375\)
\(=115,46+0,375=115,835\)
#YVA6
198,06-5,9x6
= 198,06 - 35,4
= 162,66
3/5 : 5/7 + 3/8
=21/25 +3/8
= 243/200
= 1,215
a) 12 : { 390 : [ 500 - ( 125 + 35. 7 ) ] }
= 12 : { 390 : [ 500 - ( 125 + 245 ) ] }
= 12 : { 390 : [ 500 - 370 ] }
= 12 : { 390 : 130 }
= 12 : 3
= 4
\(\frac{7}{11}:\frac{3}{5}+\frac{4}{11}x\frac{5}{6}\)
=\(\frac{7}{11}x\frac{5}{3}+\frac{20}{66}\)
=\(\frac{35}{33}+\frac{10}{33}\)
=\(\frac{45}{33}\)
=\(\frac{15}{11}\)
= 7/11 x 5/3 + 4/11 x 5/6
= 35/33 + 10/33
=15/11
CHÚC BẠN HỌC TỐT
C1: \(A=\left(\frac{36}{6}-\frac{4}{6}+\frac{3}{6}\right)-\left(\frac{150}{30}+\frac{50}{30}-\frac{45}{30}\right)-\left(\frac{18}{6}-\frac{14}{6}+\frac{15}{6}\right)\)
\(=\frac{35}{6}-\frac{155}{30}-\frac{19}{6}=\frac{35}{6}-\frac{31}{6}-\frac{19}{6}=-\frac{15}{6}=-2\frac{1}{2}\)
C2: \(6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{3}{2}-3+\frac{7}{3}-\frac{5}{2}\)
\(=\left(6-5-3\right)-\left(\frac{2}{3}+\frac{5}{3}-\frac{7}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)\)
\(=-2-0-\frac{1}{2}=-2\frac{1}{2}\)
A = 1 + (-3) +5 + (-7)+............+ 97 + (-99) + 101
A = ( -2 ) + ( - 2 ) +..........+ ( -2 ) + 101 ( có 25 số -2 )
A = -2 . 25 + 101
A = - 50 + 101
A = 51
1+3+5+.......+35+37+39
=(1+39)+(3+37)+(5+35)+.............+(19+21)
=40+40+............+40(có 10 số 40)
=40 x 10
=400
19x(39+1):2=380