



 
Hi Rita, Part a) is fairly simple, just substitute 1.2 for x into the given equation. Part b) & c) can be solved using the same method. For example, in part b) H(x)=15 so if we substitute it into the original equation: 15= 20  13x^{2} which simplifies to 0= 5  13x^{2}. The easiest way to find the time would be to solve for x using the quadratic formula. For a review on using the quadratic formula check out this review. Janice  


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