Solve the system of linear equations by substitution.

y=−4x−9
4x−y=1

x=-1, y=-5 ---> (-1, -5)

Step-by-step explanation:

so you want to plug one equation into the other. so start off by plugging y=−4x−9 into the y value of   4x−y=1> 4x-(-4x-9)=1. now subtract and isolate x which ends up being x=-1. now plug the x=-1 into either equation and isolate and solve for your y value which ends up being y=-5. you can check you answer by plugging both the x and y you found into one equation and making sure the answer it gives is true. ;)

answer

the correct answer is

explanation

the given function is

the excluded values are obtained by solving:

we factor to obtain:

the excluded values are

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional