All you need to do is to break the value into prime factors! Here is how you should work out such problem...
840
= 4 * 210
= 2² * 21 * 10
= 2² * 7 * 3 * 5 * 2
= 2³ * 3 * 5 * 7
Factoring:
Theory : A difference of two perfect cubes,
can be factored into

Proof : 




Check : 8 is the cube of 2
Check : 27 is the cube of 3
Check :
is the cube of
Check :
is the cube of 
Factorization is :

Answer:
A
Step-by-step explanation:
I did the test and it is the only one that makes sense
The graph shows the height h, in feet, of s football at time t, in seconds, from the moment it was kicked at ground level.
We are supposed to find the average rate of change in height from t=1.5 seconds to t=1.75 seconds.
Average rate of change in height=
As we can see from the the change in distance for the time interval 1.5 second to 1.75 second=
and time=
Average rate of change in height=
=20ft/sec
Hence Required Rate of change is -20 ft/sec, because its falling(In the direction of negative y-aixs)