Question

Please please help me!!

solve the system of equations by the substitution method.
{ 4x - 5y = 19
{ y = x - 4

select the correct choice below and, if necessary, fill in the answer box to complete your choice.
A. The solution is __ (Simplify your answer. Type an ordered pair.)
B. There are infinitely many solutions.
C. There is no solution.

Answer 1

A : 1,-3

so you substitute y= x-4 into 5y to make the equation look like 4x-5(x-4)=19 then you do -5 times (x-4) which should get you -5x and 20 so now the equation looks like this 4x-5x + 20 =19 then you combine like terms like 4x-5x which should get you -1x after you do that you subtract 20 from both sides of the equation and that should also get you -1 After you do all of that you divide by 1 on both sides and them you get your x term which is x= 1 now you can plug that into this equation y=x-4 now that equation will be y=1-4 and that is y=-3 so your answer is 1,-3

IF YOU DONT WANT TO DO ALL OF THAT BY HAND YOU CAN ALWAYS PLUG THAT EQUATION INTO DESMOS GRAPHING CALCULATOR AND YOU JUST HAVE TO FIND THE POINT WHERE THE LINE INTERSECTS

Answer 2

A. The solution is (1, -3)

Explanation:

4x - 5y = 19

y = x - 4

Since the second equation already has y isolated, you can just plug that into the first equation:

4x - 5(x - 4) = 19

4x - 5x + 20 = 19

-x = -1

x = 1

Take your x value from the previous equation answer and plug that into the second equation:

y = (1) - 4

y = -3

Final solution:

(1, -3)

If you really want to know if you're correct, just do a LS/RS check for both equations:

4(1) - 5(-3) = 19

19 = 19

LS = RS

-3 = 1 - 4

-3 = -3

LS = RS