Question 985806
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{{{sqrt(3x^2+10)}}} = {{{7}}},      -----> square both sides -----> 


{{{3x^2}}} + {{{10}}} = {{{49}}},


{{{3x^2}}} = {{{49-10}}},


{{{3x^2}}} = {{{39}}},


{{{x^2}}} = {{{39/3}}} = {{{13}}}.


{{{x}}} = +/- {{{sqrt(13)}}}.