Question

(x^2-5)(x+2)+5x= 2x^2+17

tìm x

giải chi tiết giúp mình nha

Answer 1

\(\left(x^2-5\right)\left(x+2\right)+5x=2x^2+17\)

\(\Rightarrow\left(x^3+2x^2-5x-10\right)+5x=2x^2+17\)

\(\Rightarrow x^3+2x^2-5x-10+5x=2x^2+17\)

\(\Rightarrow x^3+2x^2-10=2x^2+17\)

\(\Rightarrow x^3-10=17\)

\(\Rightarrow x^3=17+10=27\)

\(\Rightarrow x^3=3^3\)

\(\Rightarrow x=3\)

Answer 2

(x2−5)(x+2)+5x=2x2+17

⇒(x3+2x2−5x−10)+5x=2x2+17

⇒x3+2x2−5x−10+5x=2x2+17

⇒x3+2x2−10=2x2+17

⇒x3−10=17

⇒x3=17+10=27

⇒x3=33

⇒x=3