Functions problem

Problem: The graph below shows the function g, where g(x) = k(x+3)(x-3) for some constant k. If g(a-1.2)=0 and a>0, what is the value of a?

http://i55.tinypic.com/amtdsy.jpg"]h...com/amtdsy.jpg

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Originally Posted by yety124

Graph: http://i55.tinypic.com/amtdsy.jpg

Problem: The graph above shows the function g, where g(x) = k(x+3)(x-3) for some constant k. If g(a-1.2)=0 and a>0, what is the value of a?

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If you plug a-1.2 in for x, you get . So either or ; however, a>0...so which answer will it be?