I need help on two math problems?

Question

Sketch the graph of each linear equation. Be sure to find and show the x- and y- intercept.

y= 3x - 4

The answer is (0,-4) (4/3,0). How did they get the answer?

3x - y=6

The answer is (0,-6) (2,0). How did they get the answer?

Thanks

Answer 1

plug them in a ti84 calculator! duh

Answer 2

The y intercept is the b in y = mx + b

y = 3x -4, so the y intercept is -4.  

X is 0 when it intercepts y, so the point is (0,-4)

The x intercept is when y = 0

3x - 4 = 0

3x = 4

x =4/3

The point is (4/3,0)

To sketch it, you can find other points (make up values of x and find y).

Answer 3

You substiture 0 in for each of the variable.

To get (0,-4):

You substitute 0 in for X, because you are trying to find the y-intercept (which is when x=0). When you do that, you'll get y= -4 so the coordinate is (0,-4)

To get (4/3,0):

You substitutre 0 in for Y, and THIS time you are finding the x-intercept (which is when y=0). Then you just solve for the variable, I assume you know how to do that.

It's the same thing for the second equation, too. Just substitute 0 in and solve for the remaining variable.

Answer 4

To find the x intercept, set y=0 and solve for x.

y = 3x - 4

0 = 3x - 4

4 = 3x

4/3 = x

So when y=0, x=4/3. So (4/3, 0) is the x intercept.

to find the y intercept, set x=0 and solve for y

y = 3x - 4

y = 3(0) - 4

y = -4

So when x=0, y=(-4). Therefore, (0,-4) is the y intercept.

See if you can work the second problem using the same method.