ko phải toán lớp 6

5) 24*(15+49)+12*(50+42)

=24*64+12*92

=24*64+12*2*46

=24*64+24*46

=24*(64+46)

=24*110

=2640

65536

387420489

33554432

536870912

390625

6561

2⁴ . 2⁶ . 2 = 2¹¹

3⁵ . 27 . 81 . 3⁶ = 3⁵ . 3³ . 3⁴ . 3⁶ = 3¹⁸

4² . 4¹⁵ . 64 = 4² . 4¹⁵ . 4³ = 4²⁰

2⁹ . 16 . 4⁸ = 2⁹ . 2⁴ . (2²)⁸ = 2⁹ . 2⁴ . 2¹⁶ = 2²⁹

5¹² : 5⁴ = 5⁸

27⁴ : 3⁴ = (27:3)⁴ = 9⁴

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

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

c) \(18^3:9^3=\left(18:9\right)^3=2^3=8\)

d) \(125^3:25^4=\left(5^3\right)^3:\left(5^2\right)^4=5^9:5^8=5\)

a, 12⁷ : 6⁷ = (12 : 6)⁷ = 2⁷ = 128.

b,27⁵ : 81³ = (3³)⁵ : (3⁴)³ = 3¹⁵ : 3¹² = 3^{15 - 12} = 3³ = 27

c,18³ : 9³ = (18 : 9)³ = 2³ = 8.

d, 125³ : 25⁴ = (5³)³ : (5²)⁴ = 5⁹ : 5⁸ = 5^{9 - 8} = 5.

Đặt \(A=\frac{1.2+2.4+3.6+4.8+5.10}{4+6.8+9.12+12.16+15.20}\)

\(\Rightarrow A=\frac{1.\left(1+2\right)+2.\left(1+2\right)+3.\left(1+2\right)+4.\left(1+2\right)+5.\left(1+2\right)}{4+2.\left(3+4\right)+3.\left(3+4\right)+4.\left(3+4\right)+5.\left(3+4\right)}\)

\(\Rightarrow A=\frac{\left(1+2+3+4+5\right).\left(1+2\right)}{4+\left(2+3+4+5\right).\left(3+4\right)}\)

\(\Rightarrow A=\frac{\left(1+5\right).5:2.\left(1+2\right)}{4+\left(2+5\right).4:2.\left(3+4\right)}\)

\(\Rightarrow A=\frac{6.5:2.3}{4+7.4:2.7}=\frac{45}{4+98}=\frac{45}{102}=\frac{15}{34}\)

Vậy \(A=\frac{15}{34}\)

Chúc bn học tốt

Câu a:

7/10.4/9 + 3/10.4/9 - 1 7/9

= 4/9.(7/10 + 3/10) - 16/9

= 4/9 - 16/9

= - 12/9

= - 4/3

Câu b:

- 5/6 + 4/9.(5/4 - 2/3).(-3)^2 + 5/9.30%

= - 5/6 + [5/9 - 8/27].9 + 5/9.3/10

= - 5/6 + 5 - 8/3 + 1/6

= (-5/6 + 1/6) - 8/3 + 5

= - 4/6 - 8/3 + 15/3

= - 2/3 - 8/3 + 15/3

= - 10/3 + 15/3

= 5/3

a,\(\frac{7}{10}\cdot\frac{4}{9}+\frac{3}{10}\cdot\frac{4}{9}-1\frac{7}{9}\)

\(=\frac{14}{45}+\frac{2}{15}-\frac{16}{9}\)

\(=\frac{14}{45}+\frac{6}{45}-\frac{80}{45}\)

\(=\frac{-60}{45}=\frac{-4}{3}\)

b,\(\frac{-5}{6}+\frac{4}{9}\cdot\left(\frac{5}{4}-\frac{2}{3}\right)\cdot\left(-3\right)^2+\frac{5}{9}\cdot30\%\)

\(=\frac{-5}{6}+\frac{4}{9}\cdot\left(\frac{7}{12}\right)\cdot9+\frac{5}{9}\cdot\frac{3}{10}\)

\(=\frac{-5}{6}+\frac{7}{3}+\frac{1}{6}\)

\(=\frac{-5}{6}+\frac{14}{6}+\frac{1}{6}\)

=\(=\frac{10}{6}=\frac{5}{3}\)

Câu c:

1/2017.(1/3 - 7/12 + 1/4) - (6 2/3 - 1,5.2^2) :5/6

= 1/2017.(4/12 - 7/12 + 3/12) - (20/3 - 1,5x 4) : 5/6

= 1/2017.0 - (20/3 - 6) x 6/5

= 0 - (20/3 - 18/3) x 6/5

= - 2/3 x 6/5

= - 4/5