Question

write an equation of the line parallel to x=9 containing the point (4,3)

Answer 1

parallel lines will have the same slope, so we need to find the slope of " x = 9 ".

Learn this...it will come in handy
VUX -- vertical line, undefined slope, represented by x = a number
HOY -- horizontal line, 0 slope, represented by y = a number

as you can see, x = 9 is a vertical line with an undefined slope. A vertical line is parallel to another vertical line. And since it has to go through points (4,3), your parallel equation to x = 9 that passes throught (4,3) is : x = 4 (which is another vertical line)