If street lights are placed at most 145 feet apart, how many street lights will be
needed for a street that is 4 miles long,
assuming that there are lights at each end
of the street?

Step-by-step explanation:

d=4 miles=4×1760 yards=7040 yards=7040×3 ft

number of lights=21120 ft

number of lights=21120/145 +1≈145.7+1=146+1=147 lights

a4 - 3a2 - 1

step-by-step explanation:

step   1   :

equation at the end of step   1   :

  ((a4) -   3a2) -   1

step   2   :

trying to factor by splitting the middle term

2.1     factoring   a4-3a2-1  

the first term is,   a4   its coefficient is   1 .

the middle term is,   -3a2   its coefficient is   -3 .

the last term, "the constant", is   -1  

360 different combinations