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18 tháng 6

Ta có: \(\left(-\frac57-\frac79+\frac{9}{11}-\frac{1}{13}\right)\cdot\left(3-\frac34\right)\)

\(=\left(-\frac57-\frac79+\frac{9}{11}-\frac{11}{13}\right)\cdot\left(\frac{12}{4}-\frac34\right)\)

\(=\left(-\frac57-\frac79+\frac{9}{11}-\frac{11}{13}\right)\cdot\frac94\)

TA có: \(\left(\frac{10}{21}+\frac{14}{27}-\frac{6}{11}+\frac{22}{39}\right):\left(2-\frac23\right)\)

\(=-\frac23\left(\frac{-5}{7}-\frac79+\frac{9}{11}-\frac{11}{13}\right):\frac43\)

\(=-\frac23\left(\frac{-5}{7}-\frac79+\frac{9}{11}-\frac{11}{13}\right)\cdot\frac34\)

\(=\left(\frac{-5}{7}-\frac79+\frac{9}{11}-\frac{11}{13}\right)\cdot\frac{-2}{4}=\left(-\frac57-\frac79+\frac{9}{11}-\frac{11}{13}\right)\cdot\frac{-1}{2}\)

Ta có: \(\frac{\left(-\frac57-\frac79+\frac{9}{11}-\frac{1}{13}\right)\cdot\left(3-\frac34\right)}{\left(\frac{10}{21}+\frac{14}{27}-\frac{6}{11}+\frac{22}{39}\right):\left(2-\frac23\right)}\)

\(=\frac{\left(-\frac57-\frac79+\frac{9}{11}-\frac{11}{13}\right)\cdot\frac94}{\left(-\frac57-\frac79+\frac{9}{11}-\frac{11}{13}\right)\cdot\frac{-1}{2}}=\frac94:\frac{-1}{2}=\frac94\cdot\left(-2\right)=-\frac92\)

18 tháng 6

Ta có: $A = \dfrac{\left(\dfrac{-5}{7} - \dfrac{7}{9} + \dfrac{9}{11} - \dfrac{11}{13}\right) \cdot \left(3 - \dfrac{3}{4}\right)}{\left(\dfrac{10}{21} + \dfrac{14}{27} - \dfrac{6}{11} + \dfrac{22}{39}\right) : \left(2 - \dfrac{2}{3}\right)}$

$A = \dfrac{\left(\dfrac{-5}{7} - \dfrac{7}{9} + \dfrac{9}{11} - \dfrac{11}{13}\right) \cdot \dfrac{9}{4}}{\left(\dfrac{10}{21} + \dfrac{14}{27} - \dfrac{6}{11} + \dfrac{22}{39}\right) : \dfrac{4}{3}}$

$A = \dfrac{\left(\dfrac{-5}{7} - \dfrac{7}{9} + \dfrac{9}{11} - \dfrac{11}{13}\right) \cdot \dfrac{9}{4}}{\left(\dfrac{10}{21} + \dfrac{14}{27} - \dfrac{6}{11} + \dfrac{22}{39}\right) \cdot \dfrac{3}{4}}$

$A = \dfrac{\left(\dfrac{-5}{7} - \dfrac{7}{9} + \dfrac{9}{11} - \dfrac{11}{13}\right) \cdot \dfrac{9}{4}}{-\dfrac{2}{3} \cdot \left(\dfrac{-5}{7} - \dfrac{7}{9} + \dfrac{9}{11} - \dfrac{11}{13}\right) \cdot \dfrac{3}{4}}$

$A = \dfrac{\dfrac{9}{4}}{-\dfrac{2}{3} \cdot \dfrac{3}{4}}$ $A = \dfrac{\dfrac{9}{4}}{-\dfrac{1}{2}}$

$A = \dfrac{9}{4} \cdot (-2)$

$A = \dfrac{-18}{4}$

$A = -4,5$

Đặt biểu thức cần tính là \(A\):
\(A=\frac{\left(\frac{-5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}\right)\left(3-\frac{3}{4}\right)}{\left(\frac{10}{21}+\frac{14}{27}-\frac{6}{11}+\frac{22}{39}\right):\left(2-\frac{2}{3}\right)}\)
  • Nhóm ở tử số:
    \(3-\frac{3}{4}=\frac{12}{4}-\frac{3}{4}=\frac{9}{4}\)
  • Nhóm ở mẫu số:
    \(2-\frac{2}{3}=\frac{6}{3}-\frac{2}{3}=\frac{4}{3}\)
Đặt ngoặc lớn ở tử số là \(N\):
\(N=\frac{-5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}\)
Đặt ngoặc lớn ở mẫu số là \(D\) và biến đổi bằng cách đưa nhân tử chung \(-\frac{2}{3}\) ra ngoài:
\(D=\frac{10}{21}+\frac{14}{27}-\frac{6}{11}+\frac{22}{39}\)
\(D=-\frac{2}{3}\cdot \left(\frac{-5}{7}\right)-\frac{2}{3}\cdot \left(\frac{-7}{9}\right)-\frac{2}{3}\cdot \left(\frac{9}{11}\right)-\frac{2}{3}\cdot \left(\frac{-11}{13}\right)\)
\(D=-\frac{2}{3}\cdot \left(\frac{-5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}\right)=-\frac{2}{3}\cdot N\)
Thay \(N\), \(D\) và các giá trị đã tính ở Bước 1 vào biểu thức \(A\):
\(A=\frac{N\cdot \frac{9}{4}}{\left(-\frac{2}{3}\cdot N\right):\frac{4}{3}}\)
Rút gọn biểu thức ở mẫu số trước:
\(\left(-\frac{2}{3}\cdot N\right):\frac{4}{3}=-\frac{2}{3}\cdot N\cdot \frac{3}{4}=-\frac{1}{2}\cdot N\)
Khi đó biểu thức \(A\) trở thành:
\(A=\frac{N\cdot \frac{9}{4}}{-\frac{1}{2}\cdot N}\)
Triệt tiêu \(N\) ở cả tử và mẫu (vì \(N \neq 0\)):
\(A=\frac{\frac{9}{4}}{-\frac{1}{2}}=\frac{9}{4}\cdot (-2)=-\frac{9}{2}\)
Kết luận\(\text{Kt\ qu\ ca\ phép\ tính\ là:\ }-\frac{9}{2}\text{\ (hoc\ }-4.5\text{)}\)
S
9 tháng 9 2025

\(1)2^8:2^4+3^2\cdot3=2^4+3^3=16+27=43\)

\(2)3^{24}:3^{21}+2^2\cdot2^3=3^3+2^5=27+32=59\)

\(3)5^9:5^7+12\cdot3+7^0=5^2+36+1=25+37=62\)

\(4)5^6:5^4+3^2-2021^0=5^2+3^2-1=25+9-1=33\)

\(5)3^{19}:3^{16}+5^2\cdot2^3-1^{2021}=3^3+25\cdot8-1=27+200-1=226\)

\(6)3^6:3^5+2\cdot2^3+2021^0=3^1+2^4+1=3+16+1=20\)

9 tháng 9 2025

1: \(3^2\cdot5^3+9^2\)

\(=9\cdot125+81\)

=1125+81

=1206

2: \(55+45:3^2\)

\(=55+45:9\)

=55+5

=60

3: \(8^3:4^2-5^2=64:16-25=4-25=-21\)

4: \(5\cdot3^2-32:2^2=5\cdot9-32:4=45-8=37\)

5: \(16:2^3+5^2\cdot4=16:8+25\cdot4\)

=2+100

=102

6: \(5\cdot2^2-18:3^2\)

\(=5\cdot4-18:9\)

=20-2

=18

7: \(3\cdot5^2-15\cdot2^2=3\cdot25-15\cdot4=75-60=15\)

8: \(2^3\cdot6-72:3^2=8\cdot6-72:9=48-8=40\)

9: \(5\cdot2^2-27:3^2\)

\(=5\cdot4-27:9\)

=20-3

=17

10: \(3\cdot2^4+81:3^2=3\cdot16+81:9=48+9=57\)

11: \(4\cdot5^3-32:2^5=4\cdot125-32:32=500-1=499\)

12: \(6\cdot5^2-32:2^4=6\cdot25-32:16=150-2=148\)

16 tháng 8 2025

Bài 5:

a: \(37\cdot146+46\cdot2-46\cdot37\)

\(=37\left(146-46\right)+46\cdot2\)

\(=37\cdot100+92=3700+92=3792\)

b: \(2\cdot5\cdot71+5\cdot18\cdot2+10\cdot11\)

\(=10\cdot71+10\cdot18+10\cdot11\)

\(=10\left(71+18+11\right)=10\cdot100=1000\)

c: \(135+360+65+40\)

=135+65+360+40

=200+400

=600

d: \(27\cdot75+25\cdot27-450\)

\(=27\left(75+25\right)-450\)

=2700-450

=2250

Bài 4:

a: \(32\cdot163+32\cdot837\)

\(=32\cdot\left(163+837\right)\)

\(=32\cdot1000=32000\)

b: \(2\cdot3\cdot4\cdot5\cdot25=2\cdot5\cdot4\cdot25\cdot3=3\cdot10\cdot100=3000\)

c: \(25\cdot27\cdot4=27\cdot100=2700\)

Bài 3:

a: \(128\cdot19+128\cdot41+128\cdot40\)

\(=128\cdot\left(19+41+40\right)=128\cdot100=12800\)

b: \(375+693+625+307\)

=375+625+693+307

=1000+1000

=2000

c: \(37+42-37+22\)

=37-37+42+22

=0+64

=64

d: \(21\cdot32+21\cdot68\)

\(=21\cdot\left(32+68\right)=21\cdot100=2100\)

Bài 2:

a: \(17\cdot85+15\cdot17-120\)

\(=17\left(85+15\right)-120\)

=1700-120

=1580

b: \(189+73+211+127\)

=189+211+73+127

=400+200

=600

c: \(38\cdot73+27\cdot38\)

\(=38\left(73+27\right)=38\cdot100=3800\)

Bài 1:

a: \(28\cdot76+23\cdot28-28\cdot13\)

\(=28\left(76+23-13\right)=28\cdot86=2408\)

b: \(39\cdot50+25\cdot39+75\cdot61\)

\(=39\left(50+25\right)+75\cdot61\)

\(=39\cdot75+75\cdot61=75\left(39+61\right)=75\cdot100=7500\)

c: \(32\cdot163+837\cdot32\)

\(=32\left(163+837\right)=32\cdot1000=32000\)

d: \(63+118+37+82\)

=63+37+118+82

=100+200

=300