Question

Tìm x biết:

a. 5x(x - 4) - x² + 16 = 0

b. x + 6x² + 9x³ = 0

c. x² - 4x + 3 = 0

Answer 1

a) \(5x\left(x-4\right)-x^2+16=0\)

\(4x^2-20x+16=0\)

\(\Rightarrow\orbr{\begin{cases}x=4\\x=1\end{cases}}\)

Answer 2

b) \(x+6x^2+9x^2=0\)

\(x\left(3x+1\right)^2=0\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x=-\frac{1}{3}\end{cases}}\)

Answer 3

c) \(x^2-4x+3=0\)

\(\Rightarrow\orbr{\begin{cases}x=3\\x=1\end{cases}}\)