A) 25
B) 12
C) 13
D) 7
Correct Answer: B
Solution :
\[|4\mathbf{a}+3\mathbf{b}|=\sqrt{(4\mathbf{a}+3\mathbf{b}).(4\mathbf{a}+3\mathbf{b})}\] \[=\sqrt{16|\mathbf{a}{{|}^{2}}+9|\mathbf{b}{{|}^{2}}+24\mathbf{a}.\mathbf{b}}\] \[=\sqrt{144+144+24\times 3\times 4\times \left( \frac{-1}{2} \right)}=12.\]You need to login to perform this action.
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