MATH HELP! Solve by graphing, as well as substitution?

Question

Solve these 2 by graphing ( Just coordinates)
1. 2x-y=1
3x+y= -6

2. x+2y=4
y=2x-8

Solve these by substitution

3. y=5-4x
3x-2y=12

4. 5x-6y=16
5x+y=2

5. -3x+y= -4
y= x+8

Cant thank you enough!

Answer 1

Questions 1-2:
What you need to do is graph the two lines. Graphing is very easy in slope-intercept and point-slope form. They have given you something very close to slope-intercept (y=mx+b). So, for example, the first equation becomes y=2x-1 because you add y to both sides, and subtract one from both sides (the goal is to get y alone). Do this for 3x+y= -6, too. Now, graph both those lines (remember, the number next to the x is the slope, and the number at the end is the y-intercept. So, for y=2x-1, plot a point at (0, -1), and (1,1), draw a line between them and extend it. Now, graph 3x+y= -6 too. The point where those two lines meet is the answer! (You'll probably have to turn in your graph paper). Do the same process for #2.
Questions 3-5:
Let's look at the two equations in question three, particularly the second one. It says "Take 3 times whatever x is, subtract 2 times whatever y is, and the answer will be 12" and the first one says "take 5, subtract 4 times whatever x is, and the answer will be whatever y is" and your teacher is saying "find values for x and y that will make both of those work". Now, these two equations are a pair, they're linked. We know that y is equal to 5-4x, and oh my gosh, y appears in the second equation. You just plug it in! So, you get 3x-2(5-4x)=12, which turns out to be 3x-10+8x=12, resulting in 11x=22 when you do all the algebra (you should probably show the work of how to do this). Now, can we find x? Certainly! Divide both sides by 11 and we find out that x=2. Now, we just need to figure out what y is...but, we know that y is equal to 5-4x, and we know that x is 2. So y must equal 5-8, or -3. To check this, plug in x and y to both equations (-3 does equal 5-4*2 and 12 does equal 3*2 minus -3*2...remember, when subtracting a negative you add, e.g. 2-(-5)=7). The answer is (2,-3). Repeat this for the other two problems and you're set!

Answer 2

1. 2x-y=1 [draw line between (1/2,0) and (0,-1)]
3x+y= -6 [ Draw line through (-2,0) and (0,-6)
(-1, -3) <-- point of intersection

2. x+2y=4 [ Draw line through (4,0) and (0,2)
y=2x-8 [ Draw line through (4,0) and (0,-8)
(4,0) <-- point of intersection

Solve these by substitution

3. y=5-4x
3x-2y=12
3x -2(5-4x)=12
3x-10+8x =12
11x = 22
x = 2
y= 5-4(2) = -3

4. 5x-6y=16
5x+y=2
y=2-5x
5x-6(2-5x) =16
5x -12 +30x =16
35x = 28
x = .8
y=2 - 5(.8) = -2

5. -3x+y= -4
y= x+8
-3x +x+8=-4
-2x = -12
x=6
y= x+8= 14

Answer 3

I have an t86 and I would have to look it up in the instructions. You might want to check the index on solving equations, or something on the similar heading. Hopefully someone with a 84 can help