Question

giải phương trình x^2-2x-3

Answer 1

x²-2x-3=x²+x-3x-3=x(x+1)-3(x+1)=(x-3)(x+1)

Answer 2

<=> x^2-x+3x-3
<=> x(x-1)+3(x-1)
<=> (x-1)(x+3)
<=> x-1=0 hoặc x+3= 0
<=> x = 1 <=>x = -3
Vậy S={1;-3}

Answer 3

x\(^2\) - 2x - 3

= x\(^2\) + x - 3x - 3

= x( x + 1 ) - 3( x + 1 )

= ( x+1 )( x - 3 )

Answer 4

\(x^2-2x-3=x^2-2x-2-1\)

\(=\left(x^2-1\right)-\left(2x+2\right)=\left(x-1\right)\left(x+1\right)-2\left(x+1\right)\)

\(=\left(x+1\right)\left(x-1-2\right)=\left(x+1\right)\left(x-3\right)\)

Answer 5

\(x^2-2x-3\)

= \(x^2-2x+1-4\)

= \(\left(x^2-2x+1\right)\) \(-2^2\)

= \(\left(x-1\right)^2\)\(-2^2\)

= \(\left(x-1+2\right)\left(x-1-2\right)\)

= \(\left(x+1\right)\left(x-3\right)\)