Question

Tìm​ X biết:

5​x(x-3)-4x(x+1)=(x-2)(x+2) Làm​ giúp​ mk với​

Answer 1

\(5x\left(x-3\right)-4x\left(x+1\right)=\left(x-2\right).\left(x+2\right)\)

\(\Rightarrow5x^2-15x-4x^2-4x=x^2-4\)

\(\Rightarrow5x^2-4x^2-x^2-15x-4x=-4\)

\(\Rightarrow-19x=-4\Rightarrow x=\dfrac{4}{19}\)

Vậy \(x=\dfrac{4}{19}\)

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Answer 2

\(5x\left(x-3\right)-4x\left(x+1\right)=\left(x-2\right)\left(x+2\right)\)

\(\Leftrightarrow5x^2-15x-4x^2-4x=x^2-4\)

\(\Leftrightarrow x^2-19x=x^2-4\)

\(\Leftrightarrow19x=4\)

\(\Leftrightarrow x=\dfrac{4}{19}\)

Vậy \(x=\dfrac{4}{19}\)

Answer 3

5​x(x-3)-4x(x+1)=(x-2)(x+2)

<=> 5x² - 15x - 4x² - 4x = x² + 2x - 2x - 4

<=> 5x² - 15x - 4x² - 4x - x² - 2x + 2x = - 4

<=> 11x = - 4

<=> x = - 11/4

Answer 4

\(5x(x-3)-4x(x+1)=(x-2)(x+2)\)

\(5x^2-15x-4x^2-4x=x\left(x+2\right)-2\left(x+2\right)\)

\(5x^2-4x^2-19x=x^2+2x-2x-4\)

\(x^2-19x=x^2-4\)

\(19x=4\Leftrightarrow x=\dfrac{19}{4}\)