\(a,\left(48\cdot0,75-240:10\right)-\left(16\cdot0,5-16:4\right)\)

\(=\left(48\cdot0,75-240\cdot0,1\right)-\left(16:2-16:4\right)\)

\(=\left(36-24\right)-\left(8-4\right)\)

\(=12-4=8\)

\(b,\left(\frac{1}{2}+\frac{3}{5}-\frac{2}{15}\right):\frac{3}{5}\)

\(=\left(\frac{11}{10}-\frac{2}{15}\right):\frac{3}{5}\)

\(=\frac{29}{30}:\frac{3}{5}=\frac{145}{90}=\frac{29}{18}\)

\(c,\left(\frac{13}{84}\cdot\frac{2}{5}-\frac{1}{2}\cdot\frac{7}{180}\right):\frac{27}{18}+\frac{1}{2}\cdot\frac{1}{10}\)

\(=\left(\frac{26}{420}-\frac{7}{360}\right):\frac{3}{2}+\frac{1}{20}\)

\(=\left(\frac{13}{210}-\frac{7}{360}\right):\frac{3}{2}+\frac{1}{20}\)

\(=\frac{107}{2520}:\frac{3}{2}+\frac{1}{20}\)

\(=\frac{214}{7560}+\frac{1}{20}=\frac{214}{7560}+\frac{378}{7560}\)

\(=\frac{592}{7560}=\frac{74}{945}\)

Trả lời:

a, \(\left(48\times0,75-240\div10\right)-\left(16\times0,5-16\div4\right)\)

\(=\left(36-24\right)-\left(8-4\right)\)

\(=12-4\)

\(=8\)

b,\(\left(\frac{1}{2}+\frac{3}{5}-\frac{2}{15}\right)\div\frac{3}{5}\)

\(=\left(\frac{11}{10}-\frac{2}{15}\right)\times\frac{5}{3}\)

\(=\frac{29}{30}\times\frac{5}{3}\)

\(=\frac{29}{18}\)

c,\(\left(\frac{13}{84}\times\frac{2}{5}-\frac{1}{2}\times\frac{7}{180}\right)\div\frac{27}{18}+\frac{1}{2}\times\frac{1}{10}\)

\(=\left(\frac{13}{210}-\frac{7}{360}\right)\times\frac{18}{27}+\frac{1}{2}\times\frac{1}{10}\)

\(=\frac{107}{2520}\times\frac{18}{27}+\frac{1}{20}\)

\(=\frac{107}{3780}+\frac{1}{20}\)

\(=\frac{74}{945}\)

8/5  của 5 /7 là 40 /35 hay 8 /7 

đúng không ???

               Bài giải

\(\frac{8}{5}\text{ của }\frac{5}{7}là:\)

\(\frac{5}{7}\times\frac{8}{5}=\frac{40}{35}\text{rút gọn bằng}\frac{40\div5}{35\div5}=\frac{8}{7}.\)

               Đáp số : \(\frac{8}{7}.\)

\(\left(a\right)2,52:0,56\cdot7,2:2,5\)

\(=4,5\cdot7,2:2,5\)

\(=32,4:2,5=12,96\)

\(\left(b\right)4,36+13,734:13,08-2,716\)

\(=4,36+1,05-2,716\)

\(=5,41-2,716=2,694\)

\(\left(c\right)\frac{5}{13}\cdot\left(\frac{5}{20}-\frac{1}{10}\right)+\frac{2}{5}\)

\(=\frac{5}{13}\cdot\left(\frac{5}{20}-\frac{2}{20}\right)+\frac{2}{5}\)

\(=\frac{5}{13}\cdot\frac{3}{20}+\frac{2}{5}\)

\(=\frac{15}{260}+\frac{2}{5}=\frac{15}{260}+\frac{104}{260}\)

\(=\frac{119}{260}\)

Trả lời:

a, \(2,52\div0,56\times7,2\div2,5\)

\(=4,5\times7,2\div2,5\)

\(=32,4\div2,5\)

\(=12,96\)

b,\(4,36+13,734\div13,08-2,716\)

\(=4,36+1,05-2,716\)

\(=5,41-2,716\)

\(=2,694\)

c,\(\frac{5}{13}\times\left(\frac{5}{20}-\frac{1}{10}\right)+\frac{2}{5}\)

\(=\frac{5}{13}\times\frac{3}{20}+\frac{2}{5}\)

\(=\frac{3}{52}+\frac{2}{5}\)

\(=\frac{119}{260}\)

a) x²- 2x - 4y² - 4y = (x² - 2x + 1) - (4y² + 4y + 1) = (x - 1)² - (2y + 1)² = (x - 1 - 2y - 1)(x - 1 + 2y + 1) = (x - 2y - 2)(x + 2y)

b) x³ - 4x² + 12x - 27 = (x³ - 3x²) - (x² - 3x) + (9x - 27) = x²(x - 3) - x(x - 3) + 9(x - 3) = (x² - x + 9)(x - 3)

d) x⁴ - 2x³ + 2x - 1 = (x⁴  - 2x³ + x²) - (x² - 2x + 1) = (x² - x)² - (x - 1)² = (x² - x - x + 1)(x² - x + x - 1)

= (x² - 2x + 1)(x² - 1) = (x - 1)²(x - 1)(x + 1) = (x - 1)³(x + 1)

e) x⁴ + 2x³ - 4x - 4 = (x⁴ + 2x⁴ + x²) - (x² + 4x + 4) = (x² + x)² - (x + 2)² = (x² + x - x - 2)(x²  + x + x + 2) = (x² - 2)(x² + 2x + 2)

Viet Nam is in the Soul - East Asia . It has lots of beautiful mountains rivers and beaches . There are tow long river the mekong rivers is the south rive in the soul east asia and of couse it is longer than the red rivers . The mekong river starts in tibet and flows into to the bien dong phanxipang is the hingest mountian in Viet Nam . It 3,14 meters Viet Nam aslo has many nice beaches such as Sam Son , Nha Trang , Vung tau .

Học tốt

1. lots

2. there

3. river

4. south

5. longest

6. than

7. flows into

8. the 

9. heigh

10. has

Sửa lại tí: + (-3^x) là + 3^x vì + số lớn như vậy mà \(\frac{9^{1006}-1}{4}\)> 0 nên sửa như vậy và \(\frac{9^{1006}-1}{4}\)đổi thành \(\frac{9^{1006}+1}{4}\)

Cái đó lát nữa biết.

Bg

Ta có: 1 - 3 + 3² - 3³ +...+ 3^x = \(\frac{9^{1006}+1}{4}\)

Đặt B = 1 - 3 + 3² - 3³ +...+ 3^x:

=> B = 1 - 3 + 3² - 3³ +...+ 3^x

=> 3B = 3 - 3² + 3³ - 3⁴ +...+ 3^{x + 1}  

=> 3B + B = 3 - 3² + 3³ - 3⁴ +...+ 3^{x + 1} + (1 - 3 + 3² - 3³ +...+ 3^x)

=> 4B = 3 - 3² + 3³ - 3⁴ +...+ 3^{x + 1} + 1 - 3 + 3² - 3³ +...+ 3^x 

=> 4B = (3 - 3) + (3² - 3²) + (3³ - 3³) +...+ (3^x - 3^x) + 3^{x + 1} + 1

=> 4B = 3^{x + 1} + 1

=> B = \(\frac{3^{x+1}+1}{4}\)

=> \(\frac{3^{x+1}+1}{4}=\frac{9^{1006}+1}{4}\)

=> 3^{x + 1} + 1 = 9¹⁰⁰⁶ + 1

=> 3^{x + 1} = 9¹⁰⁰⁶

=> 3^{x + 1} = 9¹⁰⁰⁶ 

=> 3^{x + 1} = (3²)¹⁰⁰⁶

=> 3^{x + 1} = 3^2.1006 

=> 3^{x + 1} = 3²⁰¹² 

=> x + 1 = 2012

=> x       = 2012 - 1

=> x       = 2011

đề mình ra sai hay sao hả bạn

Trả lời:

\(A=\frac{2\sqrt{3+\sqrt{5-\sqrt{13+\sqrt{48}}}}}{\sqrt{6}+\sqrt{2}}\)

\(A=\frac{2\sqrt{3+\sqrt{5-\sqrt{13+4\sqrt{3}}}}}{\sqrt{6}+\sqrt{2}}\)

\(A=\frac{2\sqrt{3+\sqrt{5-\sqrt{12+4\sqrt{3}+1}}}}{\sqrt{6}+\sqrt{2}}\)

\(A=\frac{2\sqrt{3+\sqrt{5-\sqrt{\left(2\sqrt{3}+1\right)^2}}}}{\sqrt{6}+\sqrt{2}}\)

\(A=\frac{2\sqrt{3+\sqrt{5-2\sqrt{3}-1}}}{\sqrt{6}+\sqrt{2}}\)

\(A=\frac{2\sqrt{3+\sqrt{4-2\sqrt{3}}}}{\sqrt{6}+\sqrt{2}}\)

\(A=\frac{2\sqrt{3+\sqrt{3-2\sqrt{3}+1}}}{\sqrt{6}+\sqrt{2}}\)

\(A=\frac{2\sqrt{3+\sqrt{\left(\sqrt{3}-1\right)^2}}}{\sqrt{6}+\sqrt{2}}\)

\(A=\frac{2\sqrt{3+\sqrt{3}-1}}{\sqrt{6}+\sqrt{2}}\)

\(A=\frac{\sqrt{2}.\sqrt{2}.\sqrt{2+\sqrt{3}}}{\sqrt{2}.\left(\sqrt{3}+1\right)}\)

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

\(A=\frac{\sqrt{2}.\sqrt{3+2\sqrt{3}+1}}{\sqrt{2}.\left(\sqrt{3}+1\right)}\)

\(A=\frac{\sqrt{2}.\sqrt{\left(\sqrt{3}+1\right)^2}}{\sqrt{2}.\left(\sqrt{3}+1\right)}\)

\(A=\frac{\sqrt{2}.\left(\sqrt{3}+1\right)}{\sqrt{2}.\left(\sqrt{3}+1\right)}\)

\(A=1\)

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