Question

Answer 1

a: =>x^2-2x-8=x^2+2x-15

=>-2x-8=2x-15

=>-4x=-7

=>x=7/4

b: =>x^2+x-6=x^2+2x+1

=>x-6=2x+1

=>-x=7

=>x=-7
c: =>(2x-3)(x^2+2)=0

=>2x-3=0

=>x=3/2

d: =>x(x-2)-3(x+2)=x^2+8

=>x^2-2x-3x-6=x^2+8

=>-5x=14

=>x=-14/5

Answer 2

a

<=> \(x^2-4x+2x-8=x^2+5x-3x-15\)

<=> \(x^2-2x-8-x^2-2x+15=0\)

<=> \(-4x=-7\Rightarrow x=\dfrac{7}{4}\)

b

<=> \(x^2-2x+3x-6=x^2+2x+1\)

<=> \(x^2+x-6-x^2-2x-1=0\)

<=> \(-x=7\Rightarrow x=-7\)

c

<=> \(\left(2x-3\right)\left(x^2+2\right)=0\)

\(\Rightarrow2x-3=0\\ \Rightarrow x=\dfrac{3}{2}\)

d ĐK: \(x\ne\pm2\)

<=> \(\dfrac{x\left(x-2\right)}{x^2-4}-\dfrac{3\left(x+2\right)}{x^2-4}-\dfrac{x^2+8}{x^2-4}=0\)

<=> \(x^2-2x-3x-6-x^2-8=0\)

<=> \(-5x=14\\ \Rightarrow x=-\dfrac{14}{5}\left(tm\right)\)