College Algebra I Essays - Mathematics, Algebra, Linear Algebra

College Algebra I Quetion: y= -3x , y + 3x=2 Answer: substitute y= -3x in for the y in y + 3x=2 y + 3x=2 -3x + 3x=2 0=2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Question: x + 4y=3 , 2x + 8y= -6 Answer: find what x equals x + 4y=3 x + 4y + -4y=3 + -4y x= -4y + 3 then substitute the answer that you got for x into the problem 2x + 8y= -6 and solve for y then the answer you got for y put it in x= -4y + 3 and your answer should be ~ -3=-3 which means anything works it's an IDENTITY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ question : x + -y=20 , 2x + 3y=0 Answer : find y x + -y=20 x + -x + -y=20 + -x -y= -x + 20 If you do the same thing but find x instead of y you'll get x=y + 20 so, you have -y= -x + 20 , x= y + 20 Substitute -y= -x + 20 in for the equation x= y + 20 should look like this when you substitute: x= -x + 20 + 20 and you end up with the answer: x=20 So, x= 20 take the equation -y= -x + 20 and substitute x in for the x in the equation looks like this: -y= -20 + 20 then you end up with: -y=0 then, x=20 , y=0 If your graphing it your coordinates would be: (20,0) Mathematics