Question

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

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