â) (81+19)+ 243

= 100 + 243

=  343

b) 168+ 79+132

= (168+132)+79

= 300 +132

=432

c) 5.25.2.16.4

=(5.2).(25.4).16

= 10.100.16

= 1000.16

= 16000

d) 32.17+32.53

= 32.(47+53)

= 32.100

= 3200

câu d mk ghi sai đề bài nhưng bài làm vẫn đúng nha bạn

bạn ấn vào đúng 0 sẽ ra kết quả, mình làm bài này rồi dễ lắm

a)\(\frac{-7}{25}.\frac{11}{13}+\frac{-7}{25}.\frac{2}{13}-\frac{18}{25}\)

\(=\frac{-7}{25}.\left(\frac{11}{13}+\frac{2}{13}\right)-\frac{18}{25}\)

\(=\frac{-7}{25}.1-\frac{18}{25}\)

\(=-\frac{7}{25}-\frac{18}{25}\)

\(=-1\)

b)\(\frac{5}{7}.\frac{1}{3}-\frac{5}{7}.\frac{1}{4}-\frac{5}{7}.\frac{1}{12}\)

\(=\frac{5}{7}.\left(\frac{1}{3}-\frac{1}{4}-\frac{1}{12}\right)\)

\(=\frac{5}{7}.\left(\frac{4}{12}-\frac{3}{12}-\frac{1}{12}\right)\)

\(=\frac{5}{7}.0\)

\(=0\)

a) \(3,54.73+0,23.25+3,54.27+0,17.25\)

\(=3,54.\left(73+27\right)+25.\left(0,23+0,17\right)\)

\(=3,54.100+25.0,4\)

\(=354+10\)

\(=364\)

b) \(12,25:\left(5\frac{9}{20}-4\frac{1}{5}\right)+2,4.3\)

\(=12,25:\left(\frac{109}{20}-\frac{21}{5}\right)+7,2\)

\(=12,25:1,25+7,2\)

\(=9,8+7,2\)

\(=17\)

a,3, 54 x 73 + 0,23 x 25 + 3,54 x 27 + 0,17 x 25

a.\(12^7:6^7=\left(12:6\right)^7=2^7\)

b. \(27^5:81^3=\left(3^3\right)^5:\left(3^4\right)^3=3^{15}:3^{12}=3^3\)

c. \(18^3:9^3=\left(18:9\right)^3=2^3\)

d. \(125^3:25^4=\left(25^3\right)^3:25^4=25^9:25^4=25^5\)

12^7:6^7=(12:6)^7=2^7

27^5:81^3=(3^3)^5:(3^4)^3=3^15:3^12=3^3

18^3:9^3=(18:9)^3=2^3

125^3:25^4=(5^3)^3:(5^2)^4=5^9:5^8=5

1.

a) a=5 vì 5² = 25

b) a=3 vì 3³ = 27

2.

a)x=2 vì 5² = 25

b ) x= 4 vì 4³ = 64

c ) x=1 vì 2¹ . 2 =4

chúc bn hok giỏi

bài 1

\(a=5\)

\(b=3\)

3.Tìm x biết:

a) \(2-x=17-\left(-5\right)\)

\(2-x=22\)

\(x=2-22\)

\(x=-20\)

Vậy \(x=-20\)

b) \(2x-6=-3-\left(-7\right)\)

\(2x-6=4\)

\(2x=6+4\)

\(2x=10\)

\(x=10:2\)

\(x=5\)

Vậy \(x=5\)

c) \(\left(3x-6\right).3=3^4\)

\(\left(3x-6\right).3=81\)

\(3x-6=81:3\)

\(3x-6=27\)

\(3x=27+6\)

\(3x=33\)

\(x=33:3\)

\(x=11\)

Vậy \(x=11\)

a) \(3^{7} \cdot 27^{5} \cdot 81^{3}\)

• Đổi về cơ số 3: \(27 = 3^{3} , \textrm{ }\textrm{ } 81 = 3^{4}\).

\(3^{7} \cdot \left(\right. 3^{3} \left.\right)^{5} \cdot \left(\right. 3^{4} \left.\right)^{3} = 3^{7} \cdot 3^{15} \cdot 3^{12} = 3^{7 + 15 + 12} = 3^{34} .\)

b) \(100^{6} \cdot 1000^{5} \cdot 10 \textrm{ } 000^{3}\)

• Đổi về cơ số 10: \(100 = 10^{2} , \textrm{ }\textrm{ } 1000 = 10^{3} , \textrm{ }\textrm{ } 10 \textrm{ } 000 = 10^{4}\).

\(\left(\right. 10^{2} \left.\right)^{6} \cdot \left(\right. 10^{3} \left.\right)^{5} \cdot \left(\right. 10^{4} \left.\right)^{3} = 10^{12} \cdot 10^{15} \cdot 10^{12} = 10^{39} .\)

c) \(\frac{36^{5}}{18^{5}}\)

• Do cùng số mũ:

\(\left(\left(\right. \frac{36}{18} \left.\right)\right)^{5} = 2^{5} = 32.\)

d) \(24 \cdot 5^{2} + 5^{2} \cdot 5^{3}\)

\(= 24 \cdot 25 + 25 \cdot 125 = 600 + 3125 = 3725.\)

e) \(\frac{125^{4}}{5^{8}}\)

• Đổi về cơ số 5: \(125 = 5^{3}\).

\(\left(\right. 5^{3} \left.\right)^{4} : 5^{8} = 5^{12} : 5^{8} = 5^{12 - 8} = 5^{4} = 625.\)

TÓM lại là a) \(3^{34}\)
b) \(10^{39}\)
c) \(32\)
d) \(3725\)
e) \(625\)

bạn muốn chép đáp án hay sem cách làm///??

a: \(3^7\cdot27^5\cdot81^3\)

\(=3^7\cdot\left(3^3\right)^5\cdot\left(3^4\right)^3\)

\(=3^7\cdot3^{15}\cdot3^{12}=3^{7+15+12}=3^{34}\)

b: \(100^6\cdot1000^5\cdot10000^3\)

\(=\left(10^2\right)^6\cdot\left(10^3\right)^5\cdot\left(10^4\right)^3\)

\(=10^{12}\cdot10^{15}\cdot10^{12}=10^{15+12+12}=10^{39}\)

c: \(36^5:18^5=\left(\frac{36}{18}\right)^5=2^5=32\)

d: \(24\cdot5^2+5^2\cdot5^3\)

\(=5^2\left(24+5^3\right)\)

\(=25\cdot\left(24+125\right)=25\cdot149=3725\)

e: \(125^4:5^8=\left(5^3\right)^4:5^8=5^{12}:5^8=5^{12-8}=5^4\)

1. 336 : x = 12

x = 336 : 12

x = 28

2. (x + 7) - 25 = 13

x + 7 = 13 + 25

x + 7 = 38

x = 38 - 7

x = 31

3. 87 - (73 - x) = 20

73 - x = 87 - 20

73 - x = 67

x = 73 - 67

x = 6

4. x - 105 : 21 = 15

x - 5 = 15

x = 15 + 5

x = 20

5. (x - 36) : 18 = 12

x - 36 = 216

x = 216 + 36

x = 252