Question

Ma puteti ajuta cu ex asta? Va rog!

Answer 1

u·v=13

u=(a-1)i+3j

v=(a+2)i+3j

u·v=(a-1)·(a+2)+3·3

13=a^2+2a-a-2+9

a^2+a+9-13=0

a^2+a-4=0

Δ=1-4*1*(-4)

Δ=1+16

Δ=17

a₁=$\frac{-1-rad17}{2}$

a₂=$\frac{-1+rad17}{2}$