Toán Lớp 8: x^3 – 8 + ( x – 2 )( x + 1 ) = 0
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 8: x^3 – 8 + ( x – 2 )( x + 1 ) = 0
Comments ( 2 )
<=>$(x-2)(x^2+2x+4)+(x-2)(x+1)=0$
<=>$(x-2)(x^2+2x+4+x+1)=0$
<=>$(x-2)($x^2$+3x+5)=0$
$\\$Ta có: $x^2+3x+5
$\frac{11}{4}$ >0$\\$
(x-$\frac{3}{3}$ )^2+$\frac{11}{4}$ >0
=> $x-2=0$
<=> $x=2$