Question

B2: tìm x biết
a)x(x-2009)-2010x+2009.2010=0
b)4x²-25=0
c)x³-4x²-4x=0

Answer 1

\(a,x\left(x-2009\right)-2010x+2009.2010=0\\ =>x\left(x-2009\right)-2010\left(x-2009\right)=0\\ =>\left(x-2010\right)\left(x-2009\right)=0\\ =>\left[{}\begin{matrix}x-2010=0\\x-2009=0\end{matrix}\right.=>\left[{}\begin{matrix}x=2010\\x=2009\end{matrix}\right.\\ b,4x^2-25=0\\ =>\left(2x\right)^2-5^2=0\\ =>\left(2x-5\right)\left(2x+5\right)=0\\ =>\left[{}\begin{matrix}2x-5=0\\2x+5=0\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=-\dfrac{5}{2}\end{matrix}\right.\)