Question

Tìm x:

1) 4x²-25=0

2)x²+20=9x

3)25-(2x+3)²=0

4)x³+27=(x+3).(x-2)

5) 3x²+6x=0

6)25x²-1=0

7)3.(x-1)²-3x.(x-5)=2

8)4x²+4x+1=16

9)x²+3x=0

10) (2x-1)²-4x²+1=0

Answer 1

\(1)4x^2-25=0\)

\(<=>(2x)^2-5^2=0\)

\(<=>(2x+5)(2x-5)=0\)

\(<=>\) \(\left[{}\begin{matrix}2x+5=0\\2x-5=0\end{matrix}\right.\)           \(<=>\)    \(\left[{}\begin{matrix}x=-\dfrac{5}{2}\\x=\dfrac{5}{2}\end{matrix}\right.\)

\(3)25-(2x+3)^2=0\)

\(<=>5^2-(2x+3)^2=0\)

\(<=>(5-2x+3)(5+2x-3)=0\)

\(<=>\) \(\left[{}\begin{matrix}5-2x+3=0\\5+2x-3=0\end{matrix}\right.\)         \(<=>\) \(\left[{}\begin{matrix}x=1\\x=\dfrac{7}{21}\end{matrix}\right.\)

\(\)\(8)4x^2+4x+1=0\)

\(<=>(2x)^2+2x.1+1=0\)

\(<=>(2x+1)^2=0\)

\(<=>2x+1=0\)

\(<=>x=\dfrac{-1}{2}\)

Answer 2

ét ô ét