Quadratic formula ?
Alex will land
We seek to find
#0 = -3.9d^2 + 13.1d + 8.7#
Now apply the quadratic formula.
#d = (-13.1 +- sqrt(13.1^2 - 4 * -3.9 * 8.7))/(2 * -3.9)#
#d = (-13.1 +- sqrt(307.33))/(-7.8)#
We now use a calculator.
#d = 3.927 m or -0.568#m
A negative answer is clearly impossible so Alex will land
Hopefully this helps!
It's stated in this problem that Alex's path can be modelled by the quadratic function
The maximum value of this function will be the maximum height reached by Alex.
In order to find the maximum value of
Now, the expression
Multiplying this expression by
This expression is now equivalent to our function
According to this inequality, the function
Rounding this number to the nearest tenth gives
Therefore, Alex reaches no higher than