when the baseball hits the ground, the height will be 0.
h=0we are given that h=−16t2+64t+4.
this means that the height is 0 when −16t2+64t+4=0.−16t2+64t+4=0divide both sides by 4:−4t2+16t+1=04=0−4t2+16t+1=0 can be solved using the quadratic formula:t=−b±√b2−4ac2a, where at2+bt+c=0.at2+bt+c=−4t2+16t+1a=−4,b=16,c=1t=−b+√b2−4ac2aor−b−√b2−4ac2a−b+√b2−4ac2a=−16+√272−8=−0.06..−b−√b2−4ac2a=−16−√272−8=4.06 (3s.f.)we have 2 values for t:−0.06 and 4.06.
since time cannot be negative, only the positive value can be taken.
this is 4.06, to 3 significant figures.the time taken is 4.06 seconds.
For the equation y=-4x-41, the slope is -4. Writing a line related to this equation has two options:
If the line will be parallel to it then this is the slope of the new line as well. Use the point-slope form to write the equation, then simplify and convert into the slope intercept form.
(y-7)=-4(x--2)
y-7=-4x-8
y=-4x-1
If the line will be perpendicular to it then the slope is the negative reciprocal of the previous slope. It is 1/4.
