Question

Answer 1

1: \(\Leftrightarrow10\sqrt{2x}-6\sqrt{2x}-12\sqrt{2x}+10\sqrt{2x}=4\)

\(\Leftrightarrow2\sqrt{2x}=4\)

=>2x=4

=>x=2

2: \(\Leftrightarrow3\sqrt{3x}-10\sqrt{3x}+21\sqrt{3x}=28\)

\(\Leftrightarrow14\sqrt{3x}=28\)

=>3x=4

hay x=4/3

3: \(\Leftrightarrow6\sqrt{x-3}-15\sqrt{x-3}+14\sqrt{x-3}=15\)

\(\Leftrightarrow5\sqrt{x-3}=15\)

=>x-3=9

hay x=12

Answer 2

Xét  vuông tại C, CD là đường cao:

+)BC2+AC2=BA2(Pytago).⇒32+52=BC2.⇒BA=√32+52=√34(đvđd).+)BC2+AC2=BA2(Pytago).⇒32+52=BC2.⇒BA=32+52=34(đvđd).