Question 75644
{{{sqrt(7x)+4-1=7}}} Start with the given problem
{{{sqrt(7x)+3=7}}} Combine like terms
{{{sqrt(7x)=4}}} Subtract 3 from both sides
{{{(sqrt(7x))^2=(4)^2}}} Square both sides
{{{7x=16}}} 
{{{x=16/7}}} Divide both sides by 7. This is your answer
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Check:
{{{sqrt(7x)+4-1=7}}}
{{{sqrt(7(16/7))+4-1=7}}} Plug in {{{x=16/7}}}
{{{sqrt(cross(7)(16/cross(7)))+4-1=7}}}
{{{sqrt(16)+4-1=7}}}
{{{4+3=7}}}
{{{7=7}}} works