Question

Se considera:
a=i-j
b=2i+3j
Sa se calculeze modul de a+b (a și b sunt vectori)

Answer 1

$a = i-j \\ b = 2i+3j\\ \\ |a+b| = \Big|(i-j)+(2i+3j) \Big| = \\ \\=|i-j+2i+3j| = |3i+2j| = \\ \\ = \sqrt{3^2+2^2} = \sqrt{9+4} = \sqrt{13} \\ \\ \Rightarrow \boxed{|a+b| = \sqrt{13}}$

Answer 2

prin definitie, |xi+yj|=√(x²+y²)
atunci
|a+b|=|i-j+2i+3j|=|3i+2j|=√(3²+2²)=√13
As simple as that!!
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