- Slope-Intercept Form: y = mx + b, with m = slope and b = y-intercept.
If two lines are perpendicular, then they will have slopes that are negative reciprocals to each other. An example of negative reciprocals are 2 and -1/2
6.
Now with line 2, I have to convert it to slope intercept form. Firstly, subtract 2x on both sides of the equation:

Next, divide both sides by -5 and your slope-intercept form is

Now since 2/5 is not the negative reciprocal of -2/5, these lines are not perpendicular.
7.
It's pretty much the same process; convert to slope-intercept and determine if negative reciprocal. This time I'll brush through them:

Now since 2 is the negative reciprocal of -1/2, these lines are perpendicular.