Question 1113650
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{{{sqrt (7x)}}} -{{{sqrt (3x)}}} = {{{4}}}


{{{(sqrt(7) - sqrt(3))}}}.{{{sqrt(x)}}} = {{{4}}}


{{{sqrt(x)}}} = {{{4/(sqrt(7)-sqrt(3))}}} = rationalize the fraction = {{{4/(sqrt(7)-sqrt(3))}}}.{{{(sqrt(7)+sqrt(3))/(sqrt(7)+sqrt(3))}}} = {{{(4*(sqrt(7)+sqrt(3)))/((sqrt(7))^2-(sqrt(3))^2)}}} = {{{(4*(sqrt(7)+sqrt(3)))/(7-3)}}} = {{{sqrt(7)+sqrt(3)}}}  ====>


x = {{{(sqrt(7) + sqrt(3))^2}}} = {{{7 + 3 + 2*sqrt(7*3)}}} = {{{10+2*sqrt(21)}}} = 19.165 (approximately).
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