Answer:
top to bottom, the answers are b, c, a
Step-by-step explanation:
One way to find the solution to a system of equations is to substitute values in. For the first one,
y=2x+3
y=2x+5,
we can substitute 2x+3 =y into the second equation to get
y=2x+5
2x+3 = 2x+5
subtract 2x from both sides
3 = 5
As 3 is not equal to 5, this is never equal and therefore has no solution
For the second one,
y= 2x+7
y = (-2/3)x + 10
We can plug y=2x+7 into the second equation to get
2x + 7 = y = (-2/3)x + 10
2x + 7 = (-2/3)x + 10
add (2/3)x to both sides to make all x values on one side
2x + (2/3)x + 7 = 10
subtract 7 from both sides to make only x values on one side and only constants on the other
2x + (2/3)x = 3
(6/3)x + (2/3)x = 3
(8/3)x = 3
multiply both sides by 3 to remove a denominator
8x = 9
divide both sides by 8 to isolate x
x=9/8
There is only one value for when the equations are equal, so this has one solution
For the third one
y = x-5
2y = 2x - 10
Plug x-5 = y into the second equation
2 * y= 2*(x-5)
2 * (x-5) = 2x - 10
2x-10 = 2x-10
add 10 to both sides
2x=2x
As 2x is always equal to 2x, no matter what x is, there are infinitely many solutions for this system
