Answer:
3. C
4. A
Step-by-step explanation:
3. Distribute and simplify:
[tex]\sqrt{21}\sqrt{3} + \sqrt{21} \sqrt{14}[/tex]
= [tex]3 \sqrt{7} + 7 \sqrt{6}[/tex]
4. Multiply by the conjugate:
[tex]4(\sqrt{10} +\sqrt{6} ) / (\sqrt{10} -\sqrt{6}) (\sqrt{10} +\sqrt{6})[/tex]
Simplify and divide:
[tex]4(\sqrt{10} +\sqrt{6}) / 4[/tex]
= [tex]\sqrt{10} +\sqrt{6}[/tex]
