using formulas to find values: stopping distance, ball ht.,

Simplificatation, evaluation, linear equations, linear graphs, linear inequalities, basic word problems, etc.
nastydahitman
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using formulas to find values: stopping distance, ball ht.,

Postby nastydahitman » Fri Sep 02, 2011 9:22 pm

1) The distance D in feet it takes a car travelling at x mph to come to a full stop after hitting the brakes is given by D=1.26x^2 + 0.075x. Estimate the stopping distance for a car travelling at 40mph.

2) During the first seconds, the height h in feet of a baseball after t seconds is given by h = -16t^2 + 97t + 3.8 Estimate the height of the ball after 4 seconds.

3) The average weight W (in ounces) of a fish caught in a certain lake is given by W = 0.001x^3 + 0.03x^2 + 1.2 where x is the lenght in inches. Estimate the weight of a fish from the lake that is 14 inches long.

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maggiemagnet
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Re: using formulas to find values: stopping distance, ball h

Postby maggiemagnet » Fri Sep 02, 2011 10:20 pm

nastydahitman wrote:1) The distance D in feet it takes a car travelling at x mph to come to a full stop after hitting the brakes is given by D=1.26x^2 + 0.075x. Estimate the stopping distance for a car travelling at 40mph.

2) During the first seconds, the height h in feet of a baseball after t seconds is given by h = -16t^2 + 97t + 3.8 Estimate the height of the ball after 4 seconds.

3) The average weight W (in ounces) of a fish caught in a certain lake is given by W = 0.001x^3 + 0.03x^2 + 1.2 where x is the lenght in inches. Estimate the weight of a fish from the lake that is 14 inches long.

For each of these, plug the number they gave you into the formula they gave you, and simplify to get the answer they want.
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nastydahitman
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Re: using formulas to find values: stopping distance, ball h

Postby nastydahitman » Fri Sep 02, 2011 10:34 pm

That's the issue...word problems are my kryptonite. Any help of a walkthrough would be appreciated.

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maggiemagnet
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Re: using formulas to find values: stopping distance, ball h

Postby maggiemagnet » Sat Sep 03, 2011 12:24 am

nastydahitman wrote:That's the issue...word problems are my kryptonite. Any help of a walkthrough would be appreciated.

It's not a matter of word problems. It's just like I said: Take the number they gave you; plug it into the formula they gave you; simplify to get the answer they've asked for. I guess your book and your teacher didn't cover evaluating expressions, either, huh? Wow! :shock:

To learn how to "evaluate" (that is, how to plug numbers in for letters and get numbers out), try here.
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