Taking the square root of both the sides is the correct option which took place between first step and the second step.
" Square root is defined as when the number is multiply to itself we get the original number."
According to the question,
Given,
[tex](\frac{x+b}{2a})^{2} = \frac{b^{2}-4ac}{4a^{2} }[/tex]
Taking square root both the sides of quadratic formula we get,
[tex]=\sqrt{(\frac{x+b}{2a})^{2}} =+\sqrt{\frac{b^{2}-4ac}{4a^{2} }}[/tex]
Hence, Option(A) is the correct answer.
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