Solve the system of equations
5x-2y=16
15x-7y=51
Enter answer as ordered pair (x,y).
This is what I did:
-3(5x-2y=16)
-15x+6y=-48
15x-7y=51
--------------------
y=3, then i knew that -7+6 is -y so then how does that change the 3??????
Substitute the y
5x-2(3)=16
5x-6=16
+6 +6
5x=22
/5 /5
x=22/5
(22/5,3)
Do you know what I did. I saw that -7+6 is -y=3 so how does that change the answer. Btw the answer (22/5,3) is wrong. Could you help me.
Thank you.
ok, your first step is fine
Solve the system of equations
5x-2y=16
15x-7y=51
Enter answer as ordered pair (x,y).
This is what I did:
-3(5x-2y=16)
-15x+6y=-48
15x-7y=51
so far so good :)
I am going to sid track for a bit
You know that 24 = 2 dozen
and you know that 7 = 21/3
these are completely unrelated facts but from this knowledge I can say 24+7 = 2 dozen + 21/3
Think very hard about what I have done. I added the left sides and that will = the sum of the right side.
So
you have
-15x+6y=-48
15x-7y=51
these are 2 independent facts
Add the left sides and that will equal the sum of the right sides
-15x+15x+6y+-7y = -48+51
-1y=3
y=-3
Now you know that y=-3 just sub it into one of the original equations to get x
5x-2y=16
5x-2*-3=16
5x+6=16
5x=10
x=2
so I have x=2 and y = -3
I have substituted them into both original equations to check and they work just fine.
Your second question you have asked is almost identical. Just easier.
https://web2.0calc.com/questions/consider-the-system-of-equations_2
Learn from what I have written and try answering it for yourself
Thank you, it helps. But I dont understnad how the answer could help me find my second question, it tells me to substitute but it doesn't give deep details about the question.
Solve the system of equations
5x-2y=16 <===== multiply this equation by -3 to get
-15x+6y= - 48 now add to the other equation ( the 15x will cancel out)
15x-7y=51
- y = 3
y = -3 now sustitute this value of y into any of the equations to calculate the value of 'x'