Question

Jon throws a ball into the air off a platform. The height of the ball is given by y equal minus 2 x to the power of 2 plus 11 x plus 21 where y is the height, in feet, above the ground when the ball has traveled a horizontal distance of x feet. What is the factored form of the expression that could be used to find out how far the ball has traveled horizontally when it hits the ground?
A. (x+7)(-2X+3)
B. (x-7)(-2x-3)
C.(2x+7)(x+3)
D. (2x-7)(-x-3)

Answer 1

Answer:

B          (-2x - 3 )(x - 7) =  (x - 7)(-2x - 3 )

Step-by-step explanation:

y = -2x² + 11x + 21

find x when y is zero  (the ground)

(-2x - 3 )(x - 7) = 0

(-2x - 3 )  = 0,   (x - 7) = 0

  x = -1.5   and   x = 7   since Jon did not throw the ball behind him (remember he is standing on a platform)  the only possible answer is 7 feet in front of him, but they the question didn't ask for x, so I would answer B.  The answer I got and multiplicans are in reverse order from their choice.