Answer:

Step-by-step explanation:
Let the equation of the line be
where, 'm' is its slope and
is a point on it.
Given:
The equation of a known line is:

A point on the unknown line is:

Both the lines are perpendicular to each other.
Now, the slope of the known line is given by the coefficient of 'x'. Therefore, the slope of the known line is 
When two lines are perpendicular, the product of their slopes is equal to -1.
Therefore,

Therefore, the equation of the unknown line is determined by plugging in all the given values. This gives,

The equation of a line perpendicular to the given line and passing through (4, -6) is
.
The answer would be 2/5 because you have to put in a slope equation which gives you your answer.
So, these are actually pretty simple once you learn the equality used to solve for "x" and when to implement this method. You can use this equality to solve for a segment "x" anytime that two secant lines cutting through a circle come from the same point outside the circle.
Secant: by geometric definition is just a straight line that cuts a curve into multiple pieces.
I did one of them for you hopefully you can use my work for "a" to help you solve for "b".
For a. I got x=7.
Step-by-step explanation:
-b/2a
a=-6 and b=6
-(6)/2(-6)
=1/2 or 0.5