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a: \(-15-\left(-13+30\right)\)
\(=-15+13-30\)
\(=\left(-15-30\right)+13\)
=-45+13
=-32
b: \(225-150:\left(30+3^2\cdot5\right)\)
\(=225-150:\left(30+9\cdot5\right)\)
\(=225-150:75\)
=225-2
=223
c: \(18\cdot64+18\cdot36-1200\)
\(=18\left(64+36\right)-1200\)
\(=18\cdot100-12\cdot100\)
\(=6\cdot100=600\)
d: \(80-\left[130-\left(12-4\right)^2\right]\)
\(=80-130+\left(12-4\right)^2\)
\(=-50+8^2=64-50=14\)
a) 5. 42 - 18 : 32 = 5 . 16 -18 : 9 = 80 - 2 = 78
b) 33 .18 -33 .12 = 33 . 6 = 27 .6 = 162
c) 39 . 213 + 87 . 39 = 39 . ( 213 + 87 ) = 39 . 300 = 11700
d) 80 - [ 130 - ( 12 - 4 ) .2 ] = 80 - (130 - 8.2 ) = 80 - 114 = -34
OK
a, 20^2 - 6^ 2= 400 - 36 = 364
b,3^3 . 18 - 3^3 . 12 = 3^3 . ( 18-12) = 27 . 6 = 162
c, 39 . 213 + 87 . 39 = ( 213 + 87) . 39 = 300 . 39 = 110700
d, 80 - [ 130 - ( 12 - 4)^2] = 80 - [130 - (3^2) ] = 80 - 130 - 9 = -59
3. 33.19-33.12=33.(19-12)=33.7=189
4. 3.52-16:22=3.52-24:22=3.25-4=75-4=71
Bài 1 :
\(M=\dfrac{30-2^{20}}{2^{18}}=\dfrac{2.15-2^{20}}{2^{18}}=\dfrac{15}{2^{17}}-2^2=\dfrac{15}{2^{17}}-4< 0\left(\dfrac{15}{2^{17}}< 1\right)\)
\(N=\dfrac{3^5}{1^{2021}+2^3}=\dfrac{3^5}{9}=\dfrac{3^5}{3^2}=3^3=27\)
\(\Rightarrow M< N\)
Bài 3 :
a) \(t^2+5t-8\) khi \(t=2\)
\(=5^2+2.5-8\)
\(=25+10-8\)
\(=27\)
b) \(\left(a+b\right)^2-\left(b-a\right)^3+2021\left(1\right)\)
\(\left\{{}\begin{matrix}a=5\\b=a+1=6\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}a+b=11\\b-a=1\end{matrix}\right.\)
\(\left(1\right)=11^2-1^3+2021=121-1+2021=2141\)
c) \(x^3-3x^2y+3xy^2-y^3=\left(x-y\right)^3\left(1\right)\)
\(\left\{{}\begin{matrix}x=3\\y=2\end{matrix}\right.\) \(\Rightarrow x-y=1\)
\(\left(1\right)=1^3=1\)
1: \(78+22+18\)
\(=\left(78+22\right)+18\)
=100+18
=118
2: \(94+563+\left(106-563\right)-\left(-70\right)\)
\(=94+563+106-563+70\)
\(=\left(94+106\right)-\left(563-563\right)+70\)
=100-0+70
=170
3: \(25\cdot154-25+47\cdot25\)
\(=25\left(154-1+47\right)\)
\(=25\cdot200=5000\)
4: \(\left[5^{29}+5^{30}\left(16-11\right)\right]:5^{29}\)
\(=\left(5^{29}+5^{30}\cdot5\right):5^{29}\)
\(=\dfrac{5^{29}\cdot1+5^{29}\cdot5^2}{5^{29}}\)
\(=1+5^2=26\)
8: \(25\cdot2^3-\left(9-14\right)+\left(29-34+20\right)\)
\(=25\cdot8-\left(-5\right)+\left(-5\right)+20\)
\(=200+5-5+20\)
=220
1,a, 33-13(-18)=33-(-234)=267
b, 160.53+47.160=160.(53+47)=160.100=16000
c, 180:{150:[100:(24.2-42.3)]}
=180:{150:[100:(24.2-16.3)]}
=180:{150:[100:(48-48)]}
=180:[150:(100:0)] (loại vì ko có stn nào nhân vs 0 = 100)
d,43-23+(-11)=10+(-11)=-1
e,120.64+36.120=120.(64+36)=120.100=12000
g, 15.{72:[100-(12+45:42)]}
=15.{72:[100-(12+43)]}
=15.{72:[100-(12+64)]}
=15.[72:(100-76)]
=15.(72:24)
=15.3=45
2,a, x-36=82
x=82+36=118
b, (2x+4).8-40=24
(2x+4).8=24+40
(2x+4).8=64
2x+4=64:8
2x+4=8
2x=8-4
2x=4
x=4:2=2
c, (2x+42)-25=64:24
(2x+16)-32=64:16
(2x+16)-32=4
2x+16=4+32
2x+16=36
2x=36-16
2x=20
x=20:2=10
d, 95-x=45
x=95-45=50
e, (2x+13)-2=47-17
(2x+13)-2=30
2x+13=30+2
2x+13=32
2x=32-13
2x=19
x=19:2=9,5
g, (2x+32)-8=50:2
(2x+9)-8=25
2x+9=25+8
2x+9=33
2x=33-9
2x=24
x=24:2=12
c) Ta có: \(\dfrac{3}{5}+\dfrac{-5}{20}+\dfrac{30}{75}+\dfrac{-7}{4}\)
\(=\dfrac{3}{5}+\dfrac{2}{5}+\dfrac{-1}{4}+\dfrac{-7}{4}\)
\(=1-2=-1\)
Giải:
a)-1/12+4/3=-1/12+16/12=15/12=5/4
b)(-4/14-3/15)-(1/5-20/35-(-1)).7
=-17/35-22/35.7
=-17/35-22/5
=-171/35
c)3/5+-5/20+30/75+-7/4
=3/5+-1/4+2/5+-7/4
=(3/5+2/5)+(-1/4+-7/4)
=1+-2
=-1
d)5/6.-12/14+7/13
=-5/7+7/13
=-16/91
e)2/-9-5/-36-1/4
=-1/12-1/4
=-1/3
f)2/23+-5/12+7/18+21/23+-7/12
=(2/23+21/23)+(-5/12+-7/12)+7/18
=1+-1+7/18
=7/18
