Answer
Yes.
Work Step by Step
We know that if $av_1+bv_2=v$, then $-a+3b=5,a+b=3,2a-4b=-6$.
Thus $(-a+3b)+(a+b)=5+3\\4b=8\\b=2$
$a+b=a+2=3\\a=1$
And this satisfies the last equation because$2(1)-4(2)=2-8=-6$, thus it is in the span.
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