In this case, since one equation is in the form of x=, substitution would be best for this problem. Simply plug in 4y + 8 in place of x in the second equation, solve for y, then plug that value into the first equation to find x.
Answer:
? what are the answers from 1 and 2?
Step-by-step explanation:
Have you learned matrices yet? I'm going to use that to solve these, please refer to the photos.
I solved the system by using a matrix calculation. The work always needs to be shown and you do that by setting up the matrix like in the first photo and also writing out all your equations. In a TI calculator, to do this you press 2ND-X^-1,GO TO EDIT - [A] - 3×4- now enter the coefficient of the system of equations variables. NOW 2ND MODE- 2ND-X^-1 -GO TO MATH- ALPHA APPS
Now, if you don't know this you may be confuse so after rref([A]) was enter a matrix came up with [1 0 0 -21] in the top row this means x equal -21. So, the next row is y and it came out as [0 1 0 46] so y equals 46 and I'm going to let you figure out what z is by looking at the matrix.
SO... X=-21 Y=46 and Z=-10
Let's Test it
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Answer: Choice A 
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The R stands for "rotation". The "O" as a small subscript means "origin" which is where the x and y axis cross. The 90 degrees means we rotate 90 degrees counterclockwise. This is equivalent to 270 degrees clockwise, but writing
is not correct as we don't rotate 270 degrees counterclockwise.