Question about system of equations:
for equivalent system of equations if both equations start with a negative, what do you multiply? Do the numbers stay negative?

Question

Question about system of equations: 
for equivalent system of equations if both equations start with a negative, what do you multiply? Do the numbers stay negative?

saucvi · Answer

Example: -3x + 7y =-16
-9x + 5y = 16
how would you get an equivalent system of equations for that?

mertsj · Answer

Multiply the top equation by -3

saucvi · Answer

9x + -27y = 48 ?

mertsj · Answer

-3(7)=-21

mertsj · Answer

Better learn you multiplication tables, sonny.

saucvi · Answer

I'm not understanding this at all.

mertsj · Answer

What don't you understand about multiplying 3and 7 to get 21 and NOT 27?

saucvi · Answer

I don't understand why you multiplied 7 by -3 in the first place. I thought you multiply each variable to get an equivalent.

mertsj · Answer

To solve a system of equations you want to make the coefficients of either x or y to be opposites.

mertsj · Answer

If you multiply the first equation by -3 you will get 9x.

mertsj · Answer

In the second equation you have -9x

mertsj · Answer

9 and -9 are opposites.

saucvi · Answer

Oh okay. I think I understand most of it now. Thanks. I appreciate it.