Question

Sejam os vetores u = (1/4, 3, 2/5) e v = ( 2/7, -4,-3), podemos afirmar que u.v é:

Answer 1

$\left[\begin{array}{c}\frac14&3&\frac25\end{array}\right] \cdot \left[\begin{array}{c}\frac27&-4&-3\end{array}\right] =\dfrac14\cdot\dfrac27+3\cdot(-4)+\dfrac25\cdot(-3)=\dfrac{1}{14}-12-\dfrac{6}{5}=\\\\\\\boxed{-\dfrac{919}{70}}$

Answer 2

u=(1/4, 3,2/5)

v=(2/7,-4,-3)

u.v=1/4.2/7 +(3.-4)+(2/5.-3)

u.v=1/14-12-6/5

u.v=-79/70-12

[u.v=-919/70]

$\boxed{ \boxed{ \boxed{ \mathrm{alternativa \: \huge{ \boxed{ \mathsf{(c).}}}}}}}$