Question

3. Solve the system by graphing:
y = 1/2x + 9
y = 1/2x - 1


4.What is the solution to the following system?
y = 4x + 3
y - 6 = x

5. Is the coordinate (1, 2) a solution to the system?
y = x + 1
2x - y = 0

6. True/False: When you are looking at a graph of a system, the solution is the coordinate where the two lines cross.

Answer 1

4. y = 4x + 3
now sub 4x + 3 in for y in the other equation
y - 6 = x
4x + 3 - 6 = x
4x - x = 6 - 3
3x = 3
x = 1
now sub 1 in for x in either equation to find y
y - 6 = x
y - 6 = 1
y = 6 + 1
y = 7
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5. (1,2)
y = x + 1
2 = 1 + 1
2 = 2 (correct)

2x - y = 0
2(1) - 2 = 0
2 - 2 = 0
0 = 0 (correct)

yes...(1,2) is not a solution
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6. true...the solution is where the two lines intersect

as for question 3.....do you know how to graph ?

Answer 2

oops...for # 5....it is a solution

Answer 3

3. y = 1/2x + 9
y intercept is (0,9)
x intercept can be found by subbing in 0 for y
0 = 1/2x + 9
-1/2x = 9
x = 9/(-1/2)
x = 9 * - 2
x = - 18

plot your points (0,9) and (-18,0)

start at (-18,0)...and since the slope is 1/2....go up 1, and to the right 2, then up one, and to the right 2 and you should cross the y axis at (0,9)

y = 1/2x - 1
y intercept is (0,-1)
x intercept =
0 = 1/2x - 1
-1/2x = -1
x = -1/(-1/2)
x = -1 * -2
x = 2
x intercept is (2,0)

plot your points (0,-1) and (2,0)

start at (0,-1) ...and since slope is 1/2...go up 1 and to the right 2, then up 1, and to the right 2, and you should cross the x axis at (2,0)

Once you have graphed these lines, you will realize that they are parallel lines, and that there is no solution because the lines do not intersect