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![](https://rs.olm.vn/images/avt/0.png?1311)
1) 100 : { 250 : [ 450 - ( 4 x 53 - 22 x 25 ) ] }
= 100 : { 250 : [ 450 - ( 4 x 125 - 4 x 25 ) ] }
= 100 : { 250 : [ 450 - ( 500 - 100 ) ] }
= 100 : [ 250 : ( 450 - 400 ) ]
= 100 : ( 250 : 50 )
= 100 : 5
= 20
2) 30 : { 175 : [ 355 - ( 135 + 37 x 5 ) ] }
= 30 : { 175 : [ 355 - ( 135 + 185 ) ] }
= 30 : [ 175 : ( 355 - 320 ) ]
= 30 : ( 175 : 35 )
= 30 : 5
= 6
chúc bạn học giỏi
1) 100 : { 250 : [ 450 - ( 4 x 53 - 22 x 25 ) ] }
= 100 : { 250 : [ 450 - ( 4 x 125 - 4 x 25 ) ] }
= 100 : { 250 : [ 450 - ( 500 - 100 ) ] }
= 100 : [ 250 : ( 450 - 400 ) ]
= 100 : ( 250 : 50 )
= 100 : 5
= 20
2) 30 : { 175 : [ 355 - ( 135 + 37 x 5 ) ] }
= 30 : { 175 : [ 355 - ( 135 + 185 ) ] }
= 30 : [ 175 : ( 355 - 320 ) ]
= 30 : ( 175 : 35 )
= 30 : 5
= 6
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a)-54
b)-8
Bài 2:
a)(x-14):5=415:413
⇔(x-14):5=42
⇔(x-14):5=16
⇔x-14=80
⇔x=94
b)7x-15x=15-175
⇔-8x=-160
⇔x=20
![](https://rs.olm.vn/images/avt/0.png?1311)
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) \(x^3-3x^2y+3xy^2-y^3=\left(x-y\right)^3\left(1\right)\)
\(\left\{{}\begin{matrix}x=3\\y=2\end{matrix}\right.\) \(\Rightarrow x-y=1\)
\(\left(1\right)=1^3=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (-37) + 15 - 30
= (-22) - 30
= (-22) + (-30)
= -52
b) -25 - 30 - 35
= -25 + (-30) + (-35)
= -55 + (-35)
= -90
c) 27 - 7 x (-3)
= 27 - (-21)
= 27 + 21
= 48
d) -15 x 5 + 17 - 6 x 4
= -75 + 17 - 24
= -58 - 24
= -58 + (-24)
= -82
a) (-37) + 15 - 30 = -52
b) - 25 - 30 - 35=-90
c) 27 - 7 x ( - 3 ) = 48
d) - 15 x 5 + 17 - 6 x 4 = -82
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a) A=1+22+24+.................+2100
2A=(1+22+24+.................+2100)
2A=2+23+...+2101
2A-A=(2+23+...+2101)-(1+22+24+.................+2100)
A=2101-1
b)bạn tự làm
c) C=-1/90-1/72-1/50-1/42-1/30-1/20-1/12-1/6-1/2
\(=-\left(\frac{1}{90}+\frac{1}{72}+...+\frac{1}{2}\right)\)
\(=-\left(\frac{1}{10.9}+\frac{1}{9.8}+...+\frac{1}{2.1}\right)\)
\(=-\left(\frac{1}{10}-\frac{1}{9}+\frac{1}{9}-\frac{1}{8}+...+\frac{1}{2}-1\right)\)
\(=-\left(\frac{1}{10}-1\right)\)
\(=-\left(-\frac{9}{10}\right)=\frac{9}{10}\)
Bài 2:
cứ tính lần lượt là ra
a) \(3\times\left(-2\right)+4\times6-2^2+\left(-2\right)^2\)
\(=\left(-6\right)+24-4+4\)
\(=18-4+4\)
\(=14+4\)
\(=18\)
b) \(-25-40+3\times6\)
\(=-25-40+18\)
\(=-65+18\)
\(=-47\)
c) \(30\times\left(-10\right)-30\times90\)
\(=\left(-300\right)-2700\)
\(=-3000\)
Chúc bạn học tốt