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#### karush

##### Well-known member

- Jan 31, 2012

- 3,084

Let \(\displaystyle u=\left[ \begin{array}{c} 2 \\ 3 \\-1 \end{array} \right] \) and \(\displaystyle w=\left[ \begin{array}{c} 3 \\ -1 \\p \end{array} \right] \)

Given that u is perpendicular to \(\displaystyle w\), find the value of \(\displaystyle p\)

so by

**\(\displaystyle u \bullet w = 0\) then \(\displaystyle u \perp w\)**

*Dot Product*using TI-Nspire

*solve(dotP(u,w)=0,p)*\(\displaystyle p=3\)

(b)

Let \(\displaystyle v=\left[ \begin{array}{c} 1 \\ q \\5 \end{array} \right] \) Given that \(\displaystyle |v|=\sqrt{42}\) , find the possible values of \(\displaystyle q\)

does this mean

\(\displaystyle |\sqrt{1^2+q^2+5^2}|=\sqrt{42}\) if so \(\displaystyle q=\pm 4\)