f(x) = 5-x
To verify of the points belong to the graph of f(x), then the points should verify the equation:
For point A (2,3) , we need to verify if f(2)=3
f(2) = 5-2 = 3
The A belongs to the graph of f(x)
For Point B(-1,4), we need to verify if f(-1)=4
f(-1) = 5-(-1) = 5+1 =6
Then the point B DOES not belong to the graph of f(x).
For a point to belong to a graph, it's coordinates have to verify the expressio of the function.
We'll verify if the point A is on the graph, substituting it's coordonates into the expression of the function.
f(x)=5-x, where f(x)=y
So, yA = 5-xA
3 = 5-2
The point A(2,3) is on the graph pf the function f.
We'll check if the point B(-1,4) is on the graph.
yB = 5-xB
4 = 5-(-1)
4 = 5+1
4 = 6
The point B(-1,4) is not on the graph of f.
To verify if A(2,3) and B(-1,4) belongs to f(x) = 5-x.
We substitute the coordinates of x and of A and B in y = f(x) = 5-x and see if they satisfy:
A(2,3): y = 5-x . LHS = 3. RHS = 5-2 =3. SoA satisfies.
B(-1,4): y= 5-x. LHS = 4. RHS = 5--1 = 5+1. B does not satisfy.