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  • please solve RD sharma class 12 chapter 23 Scalar or dot product exercise Fill in the blanks question 3 maths textbook solution

please solve RD sharma class 12 chapter 23 Scalar or dot product exercise Fill in the blanks question 3 maths textbook solution

Answers (1)

best_answer

-5

Hint:

Use \vec{a}.m\vec{b}=120

Given:

If \hat{a}=2\hat{i}-7\hat{j}+\hat{k}, \hat{b}=\hat{i}+3\hat{j}-5\hat{k} and a.mb=120 then m=

Solution:

\begin{aligned} &a \cdot b=2(1)+(-7)(3)+1(-5) \\ &=2-21-5 \\ &=-24 \\ \end{aligned}

\begin{aligned} &a \cdot m b=m(a \cdot b) \\ &m(-24)=120 \\ &m=\frac{-120}{24} \\ &m=-5\end{aligned}

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