How do you figure out if y=-8 is a function?
1 answer:
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Let's check the answer
Start with equation (1). Plug in (x,y) = (-10,-1)
x + 5y = -15
-10 + 5y = -15 ... replace x with -10
-10 + 5(-1) = -15 ... replace y with -1
-10 - 5 = -15
-15 = -15 ... true equation
So we've confirmed one equation so far. Let's check the other equation
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Start with equation (2). Plug in (x,y) = (-10,-1)
y = (1/5)*x + 1
y = (1/5)*(-10) + 1 ... replace x with -10
-1 = (1/5)*(-10) + 1 ... replace y with -1
-1 = -2 + 1
-1 = -1
Since both equations are true when (x,y) = (-10,-1), this confirms the answer. Nice work on getting the correct answer.
Visually we can see the two lines crossing at (-10,-1). See the attached image. Note: 1/5 = 0.2 so the second equation can be written as y = 0.2x+1
Start with equation (1). Plug in (x,y) = (-10,-1)
x + 5y = -15
-10 + 5y = -15 ... replace x with -10
-10 + 5(-1) = -15 ... replace y with -1
-10 - 5 = -15
-15 = -15 ... true equation
So we've confirmed one equation so far. Let's check the other equation
--------------------
Start with equation (2). Plug in (x,y) = (-10,-1)
y = (1/5)*x + 1
y = (1/5)*(-10) + 1 ... replace x with -10
-1 = (1/5)*(-10) + 1 ... replace y with -1
-1 = -2 + 1
-1 = -1
Since both equations are true when (x,y) = (-10,-1), this confirms the answer. Nice work on getting the correct answer.
Visually we can see the two lines crossing at (-10,-1). See the attached image. Note: 1/5 = 0.2 so the second equation can be written as y = 0.2x+1