Answer: The answer is (c) [tex]4x^2-5=20.[/tex]
Step-by-step explanation: We are given four quadratic equations out ofehich we are to select the one which can be best solved by the square root property.
We can see that the equations [tex]x^2+4x=-3,~x^2+2x+1=0,~\textup{and}~2x^2+3x=-3[/tex] invove the single power of 'x', so hey can be solved by completing the square method.
But the equation [tex]4x^2-5=20[/tex] does not involve x, only x², so it makesthe most sense to solve this equation by square root method. The solution is as follows:
[tex]4x^2-5=20\\\\\Rightarrow 4x^2=25\\\\\\\Rightarrow x^2=\dfrac{25}{4}\\\\\\\Rightarrow x=\pm\dfrac{5}{2}.[/tex]
Thus, the correct option is (c) [tex]4x^2-5=20.[/tex]
