The Purplemath Forums

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 = -...

1) Express the answer in scientific notation to two decimals: The earth is approx. 92,900,000 miles from the sun. If 1mile = 1.61 x 10^3m, what is the distance to the sun in meters? 2) Simplify: x * x^-7 (Do not use negative exponents in the answer.) 3) Write an equivalent expression using positive ...

-7x^2 + 4

Not really sure, I just know one of the expressions is -(-7x^2+4)

I just need help figuring out the other one

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