Megan's commute to work includes an 8-mile drive and a 21-mile train ride. This expression can be used to find the total time it takes Megan to get to work, where xis her average driving speed in miles/hour. 21

(8 / x) + (21 / y)

Step-by-step explanation:

Given that:

Average driving speed = x mph

Miles driven to work = 8 mile

Miles by train to work = 21 miles

Average train speed = y

Total time taken to get to work. :

Recall : time taken = distance / speed

Hence,

Time taken =) total distance / average driving speed)

Total time taken = (8 / x) + (21 / y) hours

Total time taken = (8 / x) + (21 / y) hours

step-by-step explanation:

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.