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alyssamae07
Jul 21, 2012, 06:32 PM
please help me.. answer this question

1.
If a baseball is batted at an angle of 35 degree to the ground, the distance the ball travels can be estimated using the equation d=0.0034s^2+0.009s+0.3, where s is the speed, in kilometres per hour, and h is the distance flown, in metres. At what speed does the batter need to hit the ball in order to have a hoe run where the ball flies 125 m ? Round to he nearest tenth

ArcSine
Jul 22, 2012, 05:04 AM
You are given a formula which tells you the distance d the ball travels, when you input any particular speed s into the formula.

In this case, though, you know that you need the distance d to be 125, and you need to determine the speed s which will achieve that distance. In other words, you have

125 = 0.0034s^2 + 0.009s + 0.3

and you need to find the value(s) of s which make this true. An efficient way to do this is to first put it into standard form

0.0034s^2 + 0.009s - 124.97 = 0 (125 deducted from both sides)

and then use the quadratic formula (which you'll find in your book) to solve for s. Be aware that in many cases, a quadratic equation such as this one has two solutions, or roots, one of which might be a negative value. In a problem derived from a physical, real-world scenario like this one, you typically disregard the negative solution.