Để \(1,5\left(m-5\right)+11\) và \(7\left(m-8\right)-50,5\) bằng nhau

\(\Leftrightarrow1,5\left(m-5\right)+11=7\left(m-8\right)-50,5\)

\(\Leftrightarrow3\left(m-5\right)+22=14\left(m-8\right)-101\)

\(\Leftrightarrow3m+7=14m-213\)

\(\Leftrightarrow11m=220\)

\(\Leftrightarrow m=20\)

Vậy ...

1: \(\dfrac{4}{23}+\dfrac{5}{21}+\dfrac{1}{2}-\dfrac{4}{23}+\dfrac{16}{21}\)

\(=1+\dfrac{1}{2}\)

\(=\dfrac{3}{2}\)

2: \(\left(\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}\right)-\left(\dfrac{79}{67}-\dfrac{28}{41}\right)\)

\(=\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}-\dfrac{79}{67}+\dfrac{28}{41}\)

\(=\dfrac{1}{3}\)

\(\dfrac{7,5+1,5+\dfrac{5}{4}+\dfrac{5}{11}}{10,5+2,1+\dfrac{7}{4}+\dfrac{7}{11}}+x=\dfrac{6}{7}\)

\(\dfrac{9+\dfrac{5}{4}+\dfrac{5}{11}}{\dfrac{63}{5}+\dfrac{7}{4}+\dfrac{7}{11}}+x=\dfrac{6}{7}\)

\(\dfrac{\dfrac{36}{4}+\dfrac{5}{4}+\dfrac{5}{11}}{\dfrac{252}{20}+\dfrac{35}{20}+\dfrac{7}{11}}+x=\dfrac{6}{7}\)

\(\dfrac{\dfrac{41}{4}+\dfrac{5}{11}}{\dfrac{287}{20}+\dfrac{7}{11}}+x=\dfrac{6}{7}\)

\(\dfrac{\dfrac{451}{44}+\dfrac{20}{44}}{\dfrac{3157}{220}+\dfrac{140}{220}}+x=\dfrac{6}{7}\)

\(\dfrac{\dfrac{471}{44}}{\dfrac{3297}{220}}+x=\dfrac{6}{7}\)

\(\dfrac{5}{7}+x=\dfrac{6}{7}\)

\(x=\dfrac{6}{7}-\dfrac{5}{7}\)

\(x=\dfrac{1}{7}\)

a) x² + 11x = 0

x(x + 11) = 0

x = 0 hoặc x + 11 = 0

*) x + 11 = 0

x = -11

Vậy x = -11; x = 0

b) (2x - 3)² - (x + 4)² = 0

(2x - 3 - x - 4)(2x - 3 + x + 4) = 0

(x - 7)(3x + 1) = 0

x - 7 = 0 hoặc 3x + 1 = 0

*) x - 7 = 0

x = 7

*) 3x + 1 = 0

3x = -1

x = -1/3

Vậy x = -1/3; x = 7

c) x² + 7x = 8

x² + 7x - 8 = 0

x² - x + 8x - 8 = 0

(x² - x) + (8x - 8) = 0

x(x - 1) + 8(x - 1) = 0

(x - 1)(x + 8) = 0

x - 1 = 0 hoặc x + 8 = 0

*) x - 1 = 0

x = 1

*) x + 8 = 0

x = -8

Vậy x = -8; x = 1

Bài 1:

a)12,5 x (-5/7) + 1,5 x (-5/7)

=-5/7*(12,5+1,5)

=-5/7*14

=-10

b)(-1/4) x (6|2/11) + 3|9/11 x (-1/4)

=-1/4*(68/11+42/11)

=-1/4*10

=-5/2

c tương tự

d)\(\frac{9^8\cdot4^3}{27^4\cdot6^5}=\frac{\left(3^2\right)^8\cdot\left(2^2\right)^3}{\left(3^3\right)^4\cdot\left(2\cdot3\right)^5}=\frac{3^{16}\cdot2^6}{3^{12}\cdot2^5\cdot3^5}=\frac{3^{16}\cdot2^5\cdot2}{3^{16}\cdot3^1\cdot2^5}=\frac{2}{3}\)

Bài 2:

a)Ta có:

2⁸⁰⁰=(2⁸)¹⁰⁰=256¹⁰⁰

8²⁰⁰=(8²)¹⁰⁰=64¹⁰⁰

Vì 256¹⁰⁰>64¹⁰⁰ =>2⁸⁰⁰>8²⁰⁰

b)Ta có:

12⁴⁵=(12³)¹⁵=1728¹⁵

Vì 625¹⁵<1728¹⁵ =>625¹⁵<12⁴⁵

a) -5/7x(12,5+1,5)=-10

b) -1/4x (6I2/11+3I9/11) = -1/4x 10=-5/2

c) (-7/5 + -3/8 + -3/5+5/8): 2009/2010 = -7/4:2009/2010=-1005/574

d)3^16x 4^3/3^12x 6^5=3^4x4^3x6^5=......

bài 2)

2^800=2^4x200= 15^200> 8^200

=> 2^800>8^200

B) quên cách làm

dell   

bai o ban noi the co the ban la c ho day 

a,12,5x(-5/7)+1,5x(-5/7)

=-125/14+-15/14

=-10

2,2mu800>8 mu 200

6254 lon hon 12

\(7,5\cdot x+\left(-1,5\right)\cdot x+11=-13,6\\ 7,5\cdot x+\left(-1,5\right)\cdot x=-13,6-11\\ -13,6\\ 7,5\cdot x+\left(-1,5\right)\cdot x=-24,6\\ x\cdot\left[7,5+\left(-1,5\right)\right]=-24,6\\ x\cdot6=-24,6\\ x=\frac{-24,6}{6}\\ x=-4,1\)

` 1, 5 . ( -2/25 = 3/2 . (-2)/25 = -6/50 = -3/25 `

` 1 3/5 . (-3)/4 = 8/5 . (-3)/4 = -24/20 = -6/5 `

`-15/4 : 21/(-1) = -15/4 . (-1)/21 = 15/84 = 5/28 `

` ( -2 1/7 ) : ( -1 1/14 ) = (-15)/7 : (-15)/14 = -15/7 . (-14)/15 =  210/105 = 2 ` 

`@animephamdanhv.`

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