# Quadratic Formula

## Quadratic Formula Study Guide: Homework Help

A coin is thrown horizontally with a speed of 12m/s from the top of a bridge. If the coin strikes the sea water...

We are given the initial speed of the coin and the time it took before it hit the water. The given initial speed is the horizontal speed -- that is, the horizontal component of the initial speed. The horizontal component of the speed of an object in projectile motion remains constant. The...

Read More »

A projectile is thrown upward so that its distance above the ground after t secondes is h=-12t^2+432t.  After...

We have given h=-12t^2+432t `h(t)=-12t^2+423t` at maximum height , its velocity will be zero.So differentiate h with respect to t `h'(t)=-24t+423` `h'(t)=0 if` `-24t+423=0` `t=423/24` `t=17.63 sec.` `h''(t)=-24 <0` `Thus` t=17.63 Sec give maximum height.

We have given h=-12t^2+432t `h=-12t^2+432t` at maximum height , its velocity will be zero.So differentiate h with respect to t ,so we have `h'(t)=-24t+432` `h'(t)=0 if ` -24t+432=0 t=18 sec. Also `h''(t)=-24 <0`   Thus t=18 Sec ,  give maximum height.

If you have quadratic function (parabola) `f(x)=ax^2+bx+c` where `a<0` (as in your case) its maximum value will be `-(b^2-4ac)/(4a)`  (that is the height of vertex of parabola), and that maximum value will be reached at point `-b/(2a)` (those are seconds in your case). So in your...

Read More »

Find all degree solutions for the following cos4(theta)=-1

If you mean `cos(4theta)=-1` then `cos(4theta)=cos(pi)` `4theta=2npi+-pi` `theta=(np)/2+-pi/4` ,where  n is an integer. If you mean `cos^4(theta)=-1`  ,then this problem has no solution.

Read More »