The values for time is 1.361 and 0.828.
A quadratic equation is a second-order polynomial equation in a single variable x, ax²+bx+c=0. with a ≠ 0 .
Given: h=-16t²+35t+2
so if the height is going to be 20ft,
20 = 2+35t-16t²
16t²-35t18=0
Solve the above quadratic equation
x= -b±√b²-4ac/2a
a=16, b=-5, c=18
x=[-(-35)±√(-35)²-4*16*18]/2*16
x= [35±√73]/32
x= 35+√73/32 and x= 35-√73/32
x=1.361 and 0.828.
Hence, the values for time is 1.361 and 0.828.
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