Find the value of two numbers if their sum is 13 and their difference is 3

Consider the two numbers as

x and y

. From the given data, we write:

x−y=3

x+y=13

From the first equation, we determine a value for x.

x−y=3

Add y to both sides.

x=y+3

In the second equation, substitute x with (y+3).

x+y=13

(y+3)+y=13

Open the brackets and simplify.

y+3+y=13

2y+3=13

Subtract 3 from each side.

2y=10

Divide both sides by 2.

y=5

In the first equation, substitute y with 5.

x−y=3

x−5=3

Add 5 to each side.

x=8

guess at question:

a vertical line intersects the graph of g(x,y) = 0 at two points. what conclusion follows about the function f(x) implicitly defined by g(x,f(x)) = 0?

the domain of f(x) cannot include the x coordinate of any such vertical line.

informally, f(x) is not a function, and

g(x,y)=0 cannot be solved for y uniquely.

the relation r = {(x,y) such that g(x,y) = 0} is a function if

for all (a,b) ∊ r and (c,d) ∊ r, a=c implies b=d.

step-by-step explanation: