Question 119883
{{{sqrt(4x + 1) + 3 = 0}}}
{{{sqrt( 4x + 1) = -3}}}
{{{(sqrt(4x + 1))^2 =(-3)^2}}}
{{{4x + 1= 9}}}
{{{4x = 9 – 1}}} Subtract
{{{4x = 8}}} Divide by 2
{{{x = 2}}} is the answer
How can I check to see if this is the right answer.
You can plug this value of {{{x}}} back into the original equation, 
but first notice what you got above:
{{{(sqrt(4x + 1))^2 =(-3)^2}}}
This is telling you that what you're squaring on the right is
a negative number, so The square root on the left must be the 
negative square root, which, when squared gives a positive
Going back to:
{{{sqrt(4x + 1) + 3 = 0}}}
{{{sqrt(4*2 + 1) + 3 = 0}}}
{{{sqrt(9) = -3}}}
This is true, one of the square roots of 9 is -3.
{{{-3 = -3}}}
OK