Question

$\overset{\rightarrow}{a}$ ഒരു ഏകക സദിശമാണ് , $(\overset{\rightarrow}{x} - \overset{\rightarrow}{a}).(\overset{\rightarrow}{x}+\overset{\rightarrow}{a})=12$ ആയാൽ $\overset{\rightarrow}{x}$ ന്ടെ വലിപ്പം എത്ര?

$(\overset{\rightarrow}{x} - \overset{\rightarrow}{a}).(\overset{\rightarrow}{x}+\overset{\rightarrow}{a})=12$

• A. √8
• B. √9
• C. √10
• D. √13

Answer 1

Answer:

D. √13

$\overset{\rightarrow}{x}.\overset{\rightarrow}{x}+ \overset{\rightarrow}{x}.\overset{\rightarrow}{a}-\overset{\rightarrow}{a}.\overset{\rightarrow}{a}-\overset{\rightarrow}{a}.\overset{\rightarrow}{a}=12$

$|\overset{\rightarrow}{x}|^2-|\overset{\rightarrow}{a}|^2=12$

$|\overset{\rightarrow}{x}|^2-1=12$

$|\overset{\rightarrow}{x}|^2=13$

$|\overset{\rightarrow}{x}|=\sqrt{13}$