Please help! The following graph models the height of a model rocket, in feet, measured over time, in seconds.

How many seconds does it take for the rocket to reach the ground after takeoff?
Enter your answer as a number, like this: 42

Do not round your answer if it is a decimal.

What is the range of the data below? .8090100

Find the gradient of f(x,y,z)equals=left parenthesis x squared plus y squared plus z squared right parenthesis superscript negative 1 divided by 2 baseline plus ln left parenthesis x right parenthesis x2+y2+z2−1/2+ln(xyz) at the point left parenthesis negative 2 comma 1 comma negative 2 right parenthesis(−2,1,−2).

The equation x2 – 1x – 90 = 0 has solutions {a, b}. what is a + b?