Question

[Gia Huy To]

  giup em bai nay

em cam on thay co va cac banj trc a

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(0,25:\left(\dfrac{1}{2}x\right)-\dfrac{2}{5}=\dfrac{3}{4}\)

=>\(0,25:\left(\dfrac{1}{2}x\right)=\dfrac{3}{4}+\dfrac{2}{5}=\dfrac{23}{20}\)

=>\(\dfrac{1}{2}x=\dfrac{1}{4}:\dfrac{23}{20}=\dfrac{1}{4}\cdot\dfrac{20}{23}=\dfrac{5}{23}\)

=>\(x=\dfrac{5}{23}:\dfrac{1}{2}=\dfrac{10}{23}\)

b: \(\dfrac{-3}{4}-\dfrac{3}{8}x=\dfrac{4}{5}+\dfrac{-2}{3}\)

=>\(-\dfrac{3}{4}-\dfrac{3}{8}x=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\)

=>\(\dfrac{3}{8}x=-\dfrac{3}{4}-\dfrac{2}{15}=\dfrac{-45-8}{60}=\dfrac{-53}{60}\)

=>\(x=-\dfrac{53}{60}:\dfrac{3}{8}=\dfrac{-53}{60}\cdot\dfrac{8}{3}=\dfrac{-106}{45}\)

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

=>\(\dfrac{2}{3}x-\dfrac{5}{7}=\dfrac{22}{35}\)

=>\(\dfrac{2}{3}x=\dfrac{22}{35}+\dfrac{5}{7}=\dfrac{47}{35}\)

=>\(x=\dfrac{47}{35}:\dfrac{2}{3}=\dfrac{47}{35}\cdot\dfrac{3}{2}=\dfrac{141}{70}\)

d: 

ĐKXĐ: x<>-1/2

\(\dfrac{2x}{3}=\dfrac{10}{2x+1}\)

=>\(2x\left(2x+1\right)=10\cdot3=30\)

=>\(x\left(2x+1\right)=15\)

=>\(2x^2+x-15=0\)

=>\(2x^2+6x-5x-15=0\)

=>(x+3)(2x-5)=0

=>\(\left[{}\begin{matrix}x=-3\left(nhận\right)\\x=\dfrac{5}{2}\left(nhận\right)\end{matrix}\right.\)

e: ĐKXĐ: x<>0

\(\dfrac{11}{8}+\dfrac{13}{6}=\dfrac{85}{2x}\)

=>\(\dfrac{85}{2x}=\dfrac{11\cdot3+13\cdot4}{24}\)

=>\(\dfrac{85}{2x}=\dfrac{85}{24}\)

=>2x=24

=>x=12(nhận)

f: \(1,4x-\dfrac{2}{11}=1\dfrac{1}{5}\)

=>\(1,4x-\dfrac{2}{11}=\dfrac{6}{5}\)

=>\(1,4x=\dfrac{6}{5}+\dfrac{2}{11}=\dfrac{66+10}{55}=\dfrac{76}{55}\)

=>\(x=\dfrac{76}{55}:1,4=\dfrac{76}{77}\)

g: \(\dfrac{2}{15}:\left(1,24x\right)=\dfrac{3}{5}+\dfrac{-2}{3}\)

=>\(\dfrac{2}{15}:\left(1,24x\right)=\dfrac{9-10}{15}\)

=>\(\dfrac{2}{15}:\left(1,24x\right)=\dfrac{-1}{15}\)

=>\(1,24x=-2\)

=>\(x=-\dfrac{2}{1,24}=\dfrac{-200}{124}=\dfrac{-50}{31}\)

h: \(\dfrac{3x}{91}=\dfrac{-3}{14}\cdot\dfrac{10}{13}\)

=>\(\dfrac{3x}{91}=\dfrac{-3\cdot5}{7\cdot13}=\dfrac{-15}{91}\)

=>3x=-15

=>x=-5