Đùa dỡn tcam toi vui v à 💦💦

=)))) bn ơi bn nói bỏ ns theo tôi r mà:))

Bạn này trở lại mà hỗn😌😏  Toi ghim bn roi đay🤛

\(\Delta'=\left[-\left(2m+3\right)\right]^{^2}-4\cdot\left(m+1\right)\\ =4m^2+12m+9-4m-4\\ =4m^2+8m+5\\ =4m^2+8m+4+1\\ =\left(2m+2\right)^2+1\forall m\)

Sao lại có dấu "=" ở dòng 4 

`->` Một sự nhẫm lần thôi -)

`c-(x^2+2x+1)=x^3+3x^2 -2x^2+7`

`=> c-x^2-2x-1=x^3+3x^2 -2x^2+7`

`=> c=x^3+3x^2 -2x^2+7+x^2+2x+1`

`=c=x^3 + (3x^2 -2x^2+x^2) + 2x+(7+1)`

`=>c=x^3 + 2x^2 +2x+8`

\(-\dfrac{2}{5}\cdot\dfrac{3}{4}+\dfrac{-2}{5}+\dfrac{1}{4}=-\dfrac{2}{5}\cdot\left(\dfrac{3}{4}+\dfrac{1}{4}\right)=-\dfrac{2}{5}\cdot\dfrac{4}{4}=-\dfrac{2}{5}\cdot1=-\dfrac{2}{5}\)

\(\left(\dfrac{5}{-3}-\dfrac{1}{2}\right)\cdot\left(-\dfrac{6}{26}\right)=\left(-\dfrac{10}{6}-\dfrac{3}{6}\right)\cdot\left(-\dfrac{6}{26}\right)=-\dfrac{13}{6}\cdot\left(-\dfrac{6}{26}\right)=\dfrac{1}{2}\)

\(-\dfrac{4}{15}:\left[\left(-\dfrac{2}{3}\right)+\dfrac{3}{5}\right]=-\dfrac{4}{15}:\left(-\dfrac{10}{15}+\dfrac{9}{15}\right)=-\dfrac{4}{15}:\left(-\dfrac{1}{15}\right)=-\dfrac{4}{15}\cdot\left(-15\right)=4\)