Functions problem

**yety124** · May 30th, 2011, 11:20 PM

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?

**Chris L T521** · May 30th, 2011, 11:37 PM

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?

If you plug a-1.2 in for x, you get $g(a-1.2) = k((a-1.2)+3)((a-1.2)-3) = k(a+1.8)(a-4.2)=0$ . So either $a+1.8=0$ or $a-4.2=0$ ; however, a>0...so which answer will it be?

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