Question

$(3 + sqrt[4]{x}) times (9 - 3 sqrt[4]{x} + sqrt{x} )$
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Answer 1

$sqrt[4]{x}=t; (3+sqrt[4]{x})(9-3sqrt[4]{x}+sqrt{x})=(3+t)(3^2-3t+t^2)=3^3+t^3=27+sqrt[4]{x^3}$