HELP! I don't understand what this is asking me! Systems of Equations?

Question

HELP!  I don't understand what this is asking me!  Systems of Equations?

anonymous · Answer

A system of equations is shown below.

{-3x + 7y = -16
{-9x + 5y = 16

Part A: Create an equivalent system of equations by replacing one equation with the sum of that equation and a multiple of the other. Show the steps to do this. (6 points)

Part B: Show that the equivalent system has the same solution as the original system of equations. (4 points)

anonymous · Answer

@agent0smith @ranga @mathstudent55 @Zale101

anonymous · Answer

@texaschic101

studygurl14 · Answer

|dw:1389729146041:dw|

anonymous · Answer

OH!  Damn it I'm so dumb.  Thank you.

anonymous · Answer

Winter Break did me no good, y'know?  @StudyGurl14

studygurl14 · Answer

I know what you mean, lol

anonymous · Answer

Wait a second.  Is this what it is:

$$-3x+7y=-16$$$$\times3~~~~~\times3~~~~~\times3$$-----------------$$-9x+5y=16$$

$$-9x+21y=-48$$$$+9x+5y=16$$---------------------$$0+26y=32$$

I just want to ask why there is suddenly an equation "-9x + 21y = -48" and why you took out the negative sign from "-9 + 5y = 16" i the second step.

anonymous · Answer

@StudyGurl14

ranga · Answer

The RHS should be -32

studygurl14 · Answer

oh, sorry, that was a mistake. I made a mistake. That means that you should times it by -3, not 3, to make them opposites

anonymous · Answer

It's 'kay.  I got it resolved.