1. The function H= -16T^2+80T+5 is a parabola of the form , so to find the maximum height of the ball, we are going to find the y-coordinate of the vertex of the parabola. To find the y-coordinate of the vertex we are going to evaluate the function at the point . From our function we can infer that and , so the point \frac{-b}{2a} [/tex]will be . Lets evaluate the function at that point:
We can conclude that the ball reaches a maximum height of 105 feet.
2. Since we now know that the maximum height the ball reaches is 105 feet, we are going to replace with 105 in our function, then we are going to solve for to find how long the ball takes to reach its maximum height:
We can conclude that the ball reaches its maximum height in 2.5 seconds.
3. Just like before, we are going to replace with 5 in our original function, then we are going to solve for to find how long will take for the ball to be caught 5 feet off the ground:
We can conclude that it takes 5 seconds for the ball to be caught 5 feet off the ground.
Standard form will always have the largest exponents listed first on the left side. Then as you move to the right, the exponents will decrease. Choice B shows this with the exponents counting down (3,2). Choice D is a similar story with the exponents counting down (9,2,1,0). Think of -6x as -6x^1, and also think of the 10 as 10x^0.
Something like choice A is a non-answer because the term with the largest exponent 3 is buried in the middle, and not at the left side. The exponents are not in decreasing order. Choice C can be ruled out for similar reasons.
Side note: the largest exponent is the degree of the polynomial. This only applies to single variable polynomials.