Question

What is the total number of points of intersection of the graphs of x^2+y^2=16 and y=x?

Answer 1

replace y with x

you get
x^2+x^2=16
2x^2=16
divide both sides by 2
x^2=8
square root both sides
x=+/-2√2

there are 2 points of intersection which happen at
`(-2√(2),-2√(2))` and
`(2√(2),2√(2))`