已知向量$\stackrel{\rightharpoonup }{a}=(1,2),\stackrel{\rightharpoonup }{b}=(1,0),\stackrel{\rightharpoonup }{c}=(3,4)$．若$\lambda$为实数，$(\stackrel{\rightharpoonup }{a}+\lambda \stackrel{\rightharpoonup }{b})\parallel \stackrel{\rightharpoonup }{c}$，则$\lambda =$

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