I 23 +(-18)I-I-5 I+(-20190)
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Tính hợp lí
a) 7/-25+ -18/25+ 4/23+ 5/7+ 19/23
= ( 7/-25 + -18/25 ) + ( 4/23 + 19 /23 ) + 5/7
= -1 + 1 + 5/7
= 5/7
b) 7/19 x 8/11 + 7/19 x 3/11+ 12/19
= 7/19 x ( 8/11 + 3/11 ) + 12/19
= 7/19 + 12/19
= 1
\(b,81^{13}:3^{35}.\)
\(=\left(3^4\right)^{13}:\left(3^1\right)^{35}.\)
\(=3^{52}:3^{35}.\)
\(=3^{52-35}=3^{17}.\)
Vậy.....
\(c,128^{18}:32^{23}.\)
\(=\left(2^7\right)^{18}:\left(2^5\right)^{23}.\)
\(=2^{126}:2^{115}.\)
\(=2^{126-115}.\)
\(=2^{11}=2048.\)
Vậy.....
~ Hok tốt!!! ~ =))
Bài 1:
a; \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{7}{21}\) + (- \(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{1}{3}\) -\(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{10}{36}\)) + (\(\dfrac{8}{19}\) + \(\dfrac{11}{19}\)) - (\(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{5}{18}\)) + \(\dfrac{19}{19}\) - 0 - \(\dfrac{5}{8}\)
= 0 + 1 - \(\dfrac{5}{8}\)
= \(\dfrac{3}{8}\)
b; \(\dfrac{1}{13}\) + (\(\dfrac{-5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\)) - (\(\dfrac{12}{17}\) - \(\dfrac{5}{18}\) + \(\dfrac{7}{5}\))
= \(\dfrac{1}{13}\) - \(\dfrac{5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{12}{17}\) + \(\dfrac{5}{18}\) - \(\dfrac{7}{5}\)
= (\(\dfrac{1}{13}\) - \(\dfrac{1}{13}\)) + (\(\dfrac{12}{17}\) - \(\dfrac{12}{17}\)) + (-\(\dfrac{5}{18}\) + \(\dfrac{5}{18}\)) - \(\dfrac{7}{5}\)
= 0 + 0 + 0 - \(\dfrac{7}{5}\)
= - \(\dfrac{7}{5}\)
Bài 1 c;
\(\dfrac{15}{14}\) - (\(\dfrac{17}{23}\) - \(\dfrac{80}{87}\) + \(\dfrac{5}{4}\)) + (\(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\))
= \(\dfrac{15}{14}\) - \(\dfrac{17}{23}\) + \(\dfrac{80}{87}\) - \(\dfrac{5}{4}\) + \(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\)
= (\(\dfrac{15}{14}-\dfrac{15}{14}\)) + (\(-\dfrac{17}{23}+\dfrac{17}{23}\)) - (\(\dfrac{5}{4}\) - \(\dfrac{1}{4}\)) + \(\dfrac{80}{87}\)
= 0 + 0 - 1 + \(\dfrac{80}{87}\)
= - \(\dfrac{7}{87}\)
Bài 3:
\(=\left(\dfrac{3}{5}+\dfrac{2}{7}+\dfrac{4}{35}\right)+\left(-\dfrac{1}{2}-\dfrac{1}{9}-\dfrac{7}{18}\right)+\dfrac{1}{131}\)
\(=\dfrac{21+10+4}{35}+\dfrac{-9-2-7}{18}+\dfrac{1}{131}\)
=1/131
Bài 5:
a: Phần nguyên là 0
b: Phần nguyên là -1
1.Tính
a) (-16).10=-160
b) 23.(-5)=-115
c) (-24).(-25)=600
d) (-12)^2=144
2.Tính
a) 2316+115=2431
b) (-315)+(-15)=-330
c) (-215)+125=-90
d) (-200)+200=0
3.Hảy tính
a) (-457)+(-123)+23+237=-320
b) (-135)+48+140+(-5)=48
chúc bạn là bài tốt
`4|8x-3|+5|3-2x|=18`
`<=>4|8x-3|+5|2x-3|=18`
Nếu `x>=3/2=>|8x-3|=8x-3,|2x-3|=2x-3`
`pt<=>4(8x-3)+5(2x-3)=18`
`<=>32x-12+10x-15=18`
`<=>42x=27+18=45`
`<=>x=45/42(l)`
Nếu `x<=3/8=>|8x-3|=3-8x,|2x-3|=3-2x`
`pt<=>4(3-8x)+5(3-2x)=18`
`<=>12-32x+15-10x=18`
`<=>27-42x=18`
`<=>9=42x`
`<=>x=3/14(tm)`
Nếu `3/9<=x<=3/2=>|8x-3|=8x-3,|2x-3|=3-2x`
`pt<=>4(8x-3)+5(3-2x)=18`
`<=>32x-12+15-10x=18`
`<=>22x+3=18`
`<=>22x=15`
`<=>x=15/22(tm)`
Vậy x=15/22 hoặc x=3/14
Bài làm
| 23 + ( -18 ) | - | -5 | + ( 20190 )
= | 5 | - 5 + 1
= 5 - 5 + 1
= 1
# Chúc bạn học tốt #
Bài làm
| 23 + ( -18 ) | - | 5 | + ( -20190 )
= | 5 | - | 5 | + ( -1 )
= 5 - 5 + ( -1 )
= 0 + ( -1 )
= -1
# Chúc bạn học tốt #