Answer:
40 cm
Step-by-step explanation:
1 km = 10^5 cm, so 8 km = 8×10^5 cm
The map distance is 1/20,000 = 5×10^-5 of the real distance, so the map distance is ...
(5×10^-5)(8×10^5 cm) = 40 cm
The answers are 1/3, 2/6, 3/9, 4/12
Given a solution

, we can attempt to find another via reduction of order of the form

. This has derivatives


Substituting into the ODE yields



Now letting

, so that

, you end up with the ODE linear in


Assuming

(which is reasonable, since

is a singular point), you can divide through by

and end up with

and integrating both sides with respect to

gives

Back-substitute to solve for

:

and again to solve for

:


Alternatively, you can solve this ODE from scratch by employing the Euler substitution (which works because this equation is of the Cauchy-Euler type),

. You'll arrive at the same solution, but it doesn't hurt to know there's more than one way to solve this.
Solution:
Using Substitution Method:
-4x+7y=-5 (Equation 1)
x-3y=-5 (Equation 2)
get the value of x from Equation 2
x=3y-5 (Equation 3)
Put the value of x from Equation 3 in Equation 1
-4(3y-5)+7y=-5
-4(3y)+20+7y=-5
-12y+7y=-5-20
-5y=-25
Negative sign on both sides cancels each other
y=25/5
y=5
Putting value of y in equation 3
x=3(5)-5
x=15-5
x=10
Therefore, [x,y]=[10,5]
Using Elimination Method
-4x+7y=-5 (Equation 1)
x-3y=-5 (Equation 2)
Multiply equation 2 with -4 in order to eliminate the x term
-4(x-3y)=-5*4
-4x+12y=20 (Equation 3)
Adding Equation 1 and 3
-4x+7y=-5
-4x+12y=20
+ - = - (Change Of Sign with x and y terms)
-----------------
0x-5y = -25
-5y=-25
y=5
Substituting y’s value is Equation 1
-4x+7(5)=-5
-4x+35=-5
-4x=-40
Cancellation of negative sign on both sides
x=40/4
x=10
[x,y]=[10,5]
G=gum
c=candy
2g+3c=3.25 4g+c=2.75
c=2.75-4g
2g+3(2.75-4g)=3.25
2g+8.25-12g=3.25
-10g=5.00
g=0.50 c=2.75-4(.50)
c= 2.75-2.00
c=0.75