a: \(\left(3x-1\right)\left(-\dfrac{1}{2}x+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}3x-1=0\\5-\dfrac{1}{2}x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=10\end{matrix}\right.\)

b: \(\dfrac{2}{3}x+\dfrac{1}{2}x=\dfrac{5}{2}:\dfrac{15}{4}=\dfrac{5}{2}\cdot\dfrac{4}{15}=\dfrac{20}{30}=\dfrac{2}{3}\)

=>7/6x=2/3

hay \(x=\dfrac{2}{3}:\dfrac{7}{6}=\dfrac{2}{3}\cdot\dfrac{6}{7}=\dfrac{12}{21}=\dfrac{4}{7}\)

c: \(\left(\dfrac{44}{7}x+\dfrac{3}{7}\right)\cdot\dfrac{11}{5}=-2+\dfrac{3}{7}=-\dfrac{11}{7}\)

\(\Leftrightarrow x\cdot\dfrac{44}{7}+\dfrac{3}{7}=\dfrac{-11}{7}:\dfrac{11}{5}=\dfrac{-5}{7}\)

\(\Leftrightarrow x\cdot\dfrac{44}{7}=-\dfrac{8}{7}\)

hay \(x=-\dfrac{8}{7}:\dfrac{44}{7}=-\dfrac{2}{11}\)

a) (x - 2)² - (x + 3) - 4(x + 1) = 5

=> (x² - 4x + 4) - (x + 3) - 4x - 4 = 5

=> x² - 4x + 4 - x - 3 - 4x - 4 = 5

=> x² + (-4x - x - 4x) + (4 - 3 - 4) = 5

=> x² - 9x - 3 = 5

=> x² - 9x - 3 - 5 = 0

=> x² - 9x - 8 = 0

=> [x² - 2.x.9/2 + (9/2)² ] - 113/4 = 0

=> (x - 9/2)² - 113/4 = 0

=> (x - 9/2)² - \(\left(\sqrt{\frac{113}{4}}\right)^2\)= 0

=> \(\left(x-\frac{9}{2}-\sqrt{\frac{113}{4}}\right)\left(x+\frac{9}{2}+\sqrt{\frac{113}{4}}\right)=0\)

=> \(\hept{\begin{cases}x-\frac{9}{2}-\sqrt{\frac{113}{4}}=0\\x+\frac{9}{2}+\sqrt{\frac{113}{4}}=0\end{cases}}\Rightarrow\hept{\begin{cases}x=\frac{9+\sqrt{133}}{2}\\x=-\frac{9+\sqrt{133}}{2}\end{cases}}\)

Nếu không muốn nghiệm xấu như thế này thì bạn để vô nghiệm

b) (2x - 3)(2x + 3) - (x - 1)² - 3x(x - 5) = -44

=> (2x)² - 9 - (x² - 2x + 1) - 3x² + 15x = -44

=> 4x² - 9 - x² + 2x - 1 - 3x² + 15x = -44

=> (4x² - x² - 3x²) + (2x + 15x) + (-9 - 1) = -44

=> 17x  - 10 = -44

=> 17x = -34

=> x = -2

Vậy x = -2

tìm x biết:

(3x-1) [- 1/2x+5]=0

1/4+1/3:(2x-1)=-5

[2x+3/5]² - 9/25=0

-5(x+1/5)-1/2(x-2/3)=3/2x - 5 /6

[x+1/2]x [2/3-2x]=0

17/2-|2x-3/4|=-7/4

2/3x-1/2x =5/12

(x+1/5)²+17/25=26/25

[x.44/7+3/7].11/5-3/7=-2

3[3x-1/2]+1/9=0

Toán lớp 6Tìm x

 Trả lời  Câu hỏi tương tự

Chưa có ai trả lời câu hỏi này,bạn hãy là người đâu tiên giúp nguyenvanhoang giải bài toán này !

3(3x-1/2)^3+1/9=0

1200:[44-(2x-5)]=2^3.5

44 - ( 2x - 5 ) = 1200 : ( 2³ . 5 )

44 - ( 2x - 5 ) = 30

2x - 5 = 44 - 30

2x - 5 = 14

2x = 14 + 5

2x = 19

x = 19/2

a: \(2x^5+4x^4-7x^3-44⋮2x^2-7\)

\(\Leftrightarrow2x^5-7x^3+4x^4-14x^2+14x^2-49+5⋮2x^2-7\)

\(\Leftrightarrow2x^2-7\in\left\{1;-1;5;-5\right\}\)

hay \(x\in\left\{2;-2;1;-1\right\}\)

b: \(2x^2+3x+3⋮2x-1\)

\(\Leftrightarrow2x^2-x+4x-2+5⋮2x-1\)

\(\Leftrightarrow2x-1\in\left\{1;-1;5;-5\right\}\)

hay \(x\in\left\{1;0;3;-2\right\}\)

a, \(\left(x-2\right)^2-\left(x+3\right)^2-4\left(x+1\right)=5\)

\(\Leftrightarrow x^2-4x+4-\left(x^2+6x+9\right)-4x-4=5\)

\(\Leftrightarrow x^2-4x+4-x^2-6x-9-4x-4=5\)

\(\Leftrightarrow-14x-9=5\)

\(\Leftrightarrow-14x=14\)

\(\Leftrightarrow x=-1\)

Vậy....

b, \(\left(2x-3\right)\left(2x+3\right)-\left(x-1\right)^2-3x\left(x-5\right)=-44\)

\(\Leftrightarrow\left(2x\right)^2-3^2-\left(x^2-2x+1\right)-3x^2+15x=-44\)

\(\Leftrightarrow4x^2-9-x^2+2x-1-3x^2+15x=-44\)

\(\Leftrightarrow-10+17x=-44\)

\(\Leftrightarrow17x=-34\)

\(\Leftrightarrow x=-2\)

Vậy....

c, \(\left(5x+1\right)^2-\left(5x+3\right)\left(5x-3\right)=30\)

\(\Leftrightarrow\left(5x\right)^2+10x+1-\left[\left(5x\right)^2-3^2\right]=30\)

\(\Leftrightarrow\left(5x\right)^2+10x+1-\left(5x\right)^2+9=30\)

\(\Leftrightarrow10x+10=30\)

\(\Leftrightarrow10x=20\)

\(\Leftrightarrow x=2\)

Vậy....

d, \(\left(x+3\right)^2+\left(x-2\right)\left(x+2\right)-2\left(x-2\right)^2=7\)

\(\Leftrightarrow x^2+6x+9+x^2-4-2\left(x^2-4x+4\right)=7\)

\(\Leftrightarrow2x^2+6x+5-2x^2+8x-8=7\)

\(\Leftrightarrow14x-3=7\)

\(\Leftrightarrow14x=10\)

\(\Leftrightarrow x=\frac{10}{14}=\frac{5}{7}\)

Vậy...

câu hỏi đây

bn Nhật Hạ lm đúng r đấy

conkia

một đòn bẫy dài một mét .đặt ở đâu để có thể dùng 3600n có thể nâng tảng đá nặng 120kg?