\(\left\{{}\begin{matrix}\dfrac{1}{x}+\dfrac{1}{y}=\dfrac{5}{36}\\\dfrac{4}{x}+\dfrac{3}{y}=\dfrac{1}{2}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\dfrac{4}{x}+\dfrac{4}{y}=\dfrac{5}{9}\\\dfrac{4}{x}+\dfrac{3}{y}=\dfrac{1}{2}\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{y}=\dfrac{1}{18}\\\dfrac{1}{x}=\dfrac{1}{36}-\dfrac{1}{18}=-\dfrac{1}{36}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=18\\x=-36\end{matrix}\right.\)

\(\Delta'=4-\left(m-1\right)=5-m\)

để pt có nghiệm kép khi \(5-m=0\Leftrightarrow m=5\)

chọn B 

Phương trình có nghiệm kép khi:

\(\Delta'=4-\left(m-1\right)=0\Leftrightarrow5-m=0\)

\(\Rightarrow m=5\)

2.24.27+3.19.18+6.57.9

=2.27.24+3.18.19+6.9.57

=54.24+54.19+54.57

=54.(24+19+57)

=54.100 =5400

2.24.27+3.19.18+6.57.9

 = 57.24 + 57.18 + 57.9

= 57. ( 24 + 18 + 9 )

= 2907

Study well 

thank

9/2-1/2-1+3x=1/2+1/3

=)8/2-1+3x=5/6

=)3+3x=5/6

=)3x=5/6-3

=)3x=13/6

x=13/18

ta có: 9/2 - 1/2 - (1-3x)=1/2 + 1/3

       <=>9/2 - 1/2 - (1-3x)=5/6

       <=>1/2 - (1-3x)        =9/2-5/6

       <=>1/2 - (1-3x)        =11/3

       <=> 1 - 3x              = 19/6

       <=> 3x                   =13/6

       <=> x                     =13/18 

He's just gone out for a few minutes. (POP)

-> He's just popped out for a few minutes.

2^\(2x-3\) = 32

2^\(2x-3\) = 2⁵

2\(x\) - 3 = 5

2\(x\)     = 5 + 3

2\(x\)     = 8

  \(x\)      = 8 : 2

   \(x\)    = 4

2^{2x - 3} = 32

2^{2x - 3} = 2⁵(cùng cơ số)

⇒ 2x - 3 = 5

2x = 5 + 3

2x = 8

x = 8:2

x = 4

cái này nhóm bn lm thí nghiệm phân công nnao thì bn phải bt chứ :))

3/5:x=1/3

x=3/5:1/3

x=9/5

\(\frac{3}{5}\div x=\frac{1}{3}\)

\(x=\frac{3}{5}\div\frac{1}{3}=\frac{9}{5}\)

3/5:x=1/3

       x=3/5:1/3

       x=3/5×3/1

         x=9/5

vậy x=9/5