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a) = (-1+3) + (-5+7) + ...+ (-97+99)
= 2 + 2 + 2 + ....+ 2
= 2.(25) = 50
b) = (1+2-3-4)+...+(97+98-99-100)
= 4 + ...+ 4
= 4 x 25 = 25
Mình cũng muốn giúp lắm
Nhưng mình mới học lớp 5 thôi
Thông cảm
=> Tuoi cua chi gap 7 lan tuoi cua em
Ta co so do :
Tuoi cua chi :-...-...-...-...-...-...-...
Tuoi cua em : -...
Tuoi cua chi la :32 : ( 7 + 1 ) x 7 = 28 ( tuoi )
Tuoi cua em la : 32 - 28 = 4 ( tuoi )`
a, \(\dfrac{3}{5}\). (\(-\dfrac{9}{11}\)) + \(\dfrac{-3}{5}\).\(\dfrac{2}{11}\) + \(\dfrac{3}{5}\)
= \(\dfrac{3}{5}\).( - \(\dfrac{9}{11}\) - \(\dfrac{2}{11}\) + 1)
= \(\dfrac{3}{5}\).(- \(\dfrac{11}{11}\) + 1)
= \(\dfrac{3}{5}\).(1-1)
= \(\dfrac{3}{5}\).0
= 0
\(\frac{4^5.9^5-2.6^{10}}{2^{10}.3^9+6^9.20}=\frac{\left(4.9\right)^5-2.2^{10.}.3^{10}}{2^{10}.3^9+2^9.3^9.2^2.5}\)
\(\frac{2^{10}.3^{10}^{ }-2^{11}.3^{10}}{2^{10}.3^9+2^{11}.3^9.5}=\frac{2^{10}.3^{10}\left(1-2\right)}{2^{10}.3^9\left(1+2.5\right)}\)
\(\frac{2^{10}.3^{10}.\left(-1\right)}{2^{10}.3^9.\left(-9\right)}=\frac{-3}{-9}=\frac{1}{3}\)
a)5.(-8).2.(-3)
=[5.(-2)].[(-8).(-3)]
=-10.24
=-240
b)(45-135+72)-(45+72)
=45-135+72-45-72
=(45-45)+(72-72)-135
=0+0-135
=-135
c)3.(-5)2.2+2.(-5)-20
=3.25.2+2(-5)-20
=75.2+(-10)-20
=150+(-30)
=120
d)86.(-46)+46.27-46.41
=86.(-1).46+46.27-46.41
=-86.46+46.27-46.41
=46(-86+27-41)
=46(-100)
-4600
e)34(15-10)-15(34-10)
=34.15-34.10-15.34+15.10
=(34.15-15.34)+(15.10-34.10)
=[34(15-15)]+[10(15-34)]
=34.0+10(-9)
=0+(-90)
=-90
\(a.20-\left[30-\left(5-1\right)^2\right]\) \(b.75-\left(3.5^2-4.2^3\right)\)
\(=20-\left[30-4^2\right]\) \(=75-\left(75-4.2^3\right)\)
\(=20-14=6\) \(=75-\left(75-32\right)\)
\(=75-43=32\)
a: \(=\dfrac{-39+19+10}{12}=\dfrac{-10}{12}=\dfrac{-5}{6}\)
b: \(=\dfrac{2^{30}\cdot3^{16}\cdot7-2^{34}\cdot3^{15}}{2^{28}\cdot3^{21}-2^{28}\cdot3^{17}}\)
\(=\dfrac{2^{30}\cdot3^{15}\left(3\cdot7-2^4\right)}{2^{28}\cdot3^{17}\left(3^4-1\right)}=\dfrac{2^2}{3^2}\cdot\dfrac{21-16}{80}=\dfrac{4}{9}\cdot\dfrac{5}{80}\)
\(=\dfrac{20}{720}=\dfrac{1}{36}\)
3.(–5)2 + 2.(–5) – 20
=75+(-10)-20
=65-20=45
Học tốt
3.(–5)2 + 2.(–5) – 20
= ( -5 ) [ 3(- 5 ) + 2 ] - 20
= ( - 5 ) ( -15 + 2 ) - 20
= ( - 5 ) ( - 13 ) - 20
= 65 - 20
= 45
Study well