Show all work please If a rock falls from a height of 70 met

Show all work please.

If a rock falls from a height of 70 meters on Earth, the height H (in meters) after x seconds is approximately H(x) = 70 - 4.9x^2. When does the rock strike the ground? Round to the nearest hundredth, if necessary. 1.71 sec 14.29 sec 2.92 sec 3.78 sec

Solution

the rock will strike ground when height =0

70 -4.9x^2 =0

70 =4.9 x^2

x^2 =70/4.9

x^2 =14.28571

x =3.77888

rounding off x=3.78 sec

answer 3.78 sec option 4

thank you