Answer:
A
Step-by-step explanation:
y = -9 ------(1)
9x -4y = -9 -------(2)
substitute (1) into (2)
9x - 4 (-9) = -9
9x = - 45
x = -5
there you go, x = -5 and y = -9
so. (-5 , -9 )
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Answer:
The ball will be 84 feet above the ground 1.125 seconds and 4.5 seconds after launch.
Step-by-step explanation:
Statement is incorrect. Correct form is presented below:
<em>The height </em>
<em> of an ball that is thrown straight upward from an initial position 3 feet off the ground with initial velocity of 90 feet per second is given by equation </em>
<em>, where </em>
<em> is time in seconds. After how many seconds will the ball be 84 feet above the ground. </em>
We equalize the kinematic formula to 84 feet and solve the resulting second-order polynomial by Quadratic Formula to determine the instants associated with such height:

(1)
By Quadratic Formula:

,
The ball will be 84 feet above the ground 1.125 seconds and 4.5 seconds after launch.