Bài 1:
a: 11x+12=18-4x
=>15x=6
hay x=2/5
b: \(\Leftrightarrow7x\left(x+6\right)-\left(x+6\right)\left(x-6\right)=0\)
=>(x+6)(6x+6)=0
=>x=-6 hoặc x=-1
c: \(\Leftrightarrow\left(3x-2\right)\left(2x-3\right)=\left(6x+1\right)\left(x+7\right)\)
\(\Leftrightarrow6x^2+42x+x+7=6x^2-9x-4x+6\)
=>43x+7=-13x+6
=>56x=-1
hay x=-1/56
Bài 1
a, \(15x=6\Leftrightarrow x=\dfrac{6}{15}=\dfrac{2}{5}\)
b, \(7x\left(x+6\right)-\left(x+6\right)\left(x-6\right)=0\Leftrightarrow\left(x+6\right)\left(6x+6\right)=0\Leftrightarrow x=-1;x=-6\)
c, đk : x khác -7 ; 3/2
\(\Leftrightarrow\left(3x-2\right)\left(2x-3\right)=\left(6x+1\right)\left(x+7\right)\Leftrightarrow6x^2-13x+6=6x^2+14x+7\)
\(\Leftrightarrow-1=27x\Leftrightarrow x=-\dfrac{1}{27}\left(tm\right)\)
Bài 2 :
Gọi quãng đường AB là x ( x > 0 )
Theo bài ra ta có pt \(\dfrac{x}{50}-\dfrac{x}{70}=1+\dfrac{12}{60}=\dfrac{6}{5}\Rightarrow x=210\left(tm\right)\)
