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Bài 1:
a) x.x.y.y.x.y.x = \(x^4.y^3\)
b) 1000.10.10= 1000. \(10^2\)
c) \(3^{15}:3^5=3^{15-5}=3^{10}\)
d) \(9^8:3=3^{16}:3=3^{15}\)
e) \(125:5^3=\dfrac{125}{5^3}=\dfrac{5^3}{5^3}=1\)
B2:
1.
x.x.y.y.x.y.x=(x.x.x.x) (y.y.y)=x4.y3=(x.y)4.3=xy12
1000.10.10=103.10.10=103+1+1=105
315:35=315–5=310
98:3=(32)8:3=316:3=316–1=315
125:53=53:53=1
a) 12 : { 390 : [ 500 - ( 125 + 35. 7 ) ] }
= 12 : { 390 : [ 500 - ( 125 + 245 ) ] }
= 12 : { 390 : [ 500 - 370 ] }
= 12 : { 390 : 130 }
= 12 : 3
= 4
A = 12 : {390 : [500 - (125 + 35.7)]}
A = 12 : {390 : [500 - (125 + 245)]}
A = 12 : {390 : [500 - 370]}
A = 12 : {390 : 130}
A = 12 : 3 = 4
B = 12000 - (1500 . 2 + 1800.3 + 1800.2 : 3)
B = 12000 - (3000 + 5400 + 1200)
B = 12000 - 9600 = 2400
C = \(\frac{11\cdot3^{22}\cdot3^7-9^{15}}{\left(2\cdot3^{14}\right)^2}=\frac{11\cdot3^{22}\cdot3^7-\left(3^2\right)^{15}}{2^2\cdot3^{28}}=\frac{11\cdot3^{29}-3^{30}}{2^2\cdot3^{28}}=\frac{11\cdot3\cdot3^{28}-3^2\cdot3^{28}}{2^2\cdot3^{28}}\)
\(=\frac{33\cdot3^{28}-9\cdot3^{28}}{4\cdot3^{28}}=\frac{\left(33-9\right)\cdot3^{28}}{4\cdot3^{28}}=\frac{24}{4}=6\)
200-{30-(4-1)2
=200-{30-9}
=179
12:{390:[500-(125+35*7)]}
=12: {390 : [500- 245]}
=12 : {390 : 255}
=12 : 1,52941176471
= 7.84615384613
12000-(1500*2 + 1800 * 3+1800*2:3)
=12000-(3000+5400+3600:3)
= 12000-9600
=2400
600: { 450:[450-(4*53 - 23 *52)]}
= 600:{ 450:[450-(4*125-8*25)]}
=600:{450:[450-300]}
=600: { 450: 150}
=600 : 3
= 200
a) 23.15 - [115 - (12-5)2]
= 8.15 - [115 - 72]
= 120 - [115 - 49]
= 120 - 66
= 54
b) 30 : {175 : [355 - (135+37.5)]}
= 30 : {175 : [355 - (135 + 185)]}
= 30 : {175 : [355 - 320]}
= 30 : {175 : 35}
= 30 : 5
= 6
c) 12 : {390 : [500 - (125+35.7)]}
= 12 : {390 : [500 - (125+245)]}
= 12 : {390 : [500 - 370]}
= 12 : {390 : 130}
= 12 : 3
= 4
\(a,\left(3x+5\right)+105=200\)
\(3x+5=95\)
\(3x=90\)
\(x=90:3\)
\(x=30\)
\(b,\left(x-4\right).\left(3x-15\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-4=0\\3x-15=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=4\\x=5\end{cases}}\)
\(c,\left(72000+18000\right)-\left(3x+3000\right)=1200\)
\(90000-\left(3x+3000\right)=1200\)
\(3x+3000=88800\)
\(3x=85800\)
\(x=28600\)
\(d,\left[3.\left(2+x\right):7\right].4=120\)
\(3.\left(2+x\right):7=30\)
\(3.\left(2+x\right)=210\)
\(2+x=70\)
\(x=68\)
\(e,2480-4710:3+\left[200-\left(x-5\right)\right]=1010\)
\(2480-1570+\left(200-x+5\right)=1010\)
\(910+\left(205-x\right)=1010\)
\(205-x=100\)
\(x=105\)
\(28.76+13.28+11.28\) \(12000-\left(1500.2+1800.3+1800.2:3\right)\)
\(=28\cdot\left(76+13+11\right)\) \(=12000-9600\)
\(=28.100=2800\) \(=2400\)
Những phép sau tương tự
12 : {390 : [ 500 - (125 + 35 . 7)]}
= 12 : { 390 : [500 - 370]
= 12 : {390 : 130}
= 12 : 3
= 4
Chúc các bạn học tốt
a) 12 : { 390 : [ 500 - ( 125 + 35 x 7 ) ] }
= 12 : { 390 : [ 500 - 370 ] }
= 12 : { 390 : 130 }
= 12 : 3 = 4
b) 12000 - ( 15000 x 2 + 18000 x 3 + 18000 x 2 : 3 )
= 12000 - ( 30000 + 54000 + 12000 ) = -84000
c) 5 x { 26 - [ 3 x ( 5 + 2 x 5 ) + 15 ] : 15 }
= 5 x { 26 - [ 3 x 15 + 15 ] : 15 }
= 5 x { 26 - 60 : 15 }
= 5 x 22 = 110