Some asked in Science & MathematicsMathematics · 8 years ago

# Write the equation of the line which passes through (2, 1) and is perpendicular to x = –2. (1 point)?

need help understanding this equation step by step

Update:

but i need help solving it step by step

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• 8 years ago

Hi there --

Two things to keep in mind when solving these -- first is how to find the equation of a line, given its slope and point on the line; second how to find the slopes of perpendicular lines.

In this problem, we need to recognize that the slope of x = -2 is undefined, as it's a vertical line. This means that its slope which is generally known to be the negative reciprocals (for defined nonzero numbers) ends up being zero for the case of a line with undefined slope. All this means is that lines perpendicular to a vertical line are always horizontal and, therefore, have slope m = 0.

Given this slope, now derive the equation of the line from slope-intercept form:

y = mx + b,

using m = 0, and the point (2,1) as an instance of x, y -- to find b:

1 = 0*1 + b;

so b = 1.

Thus our equation is y = 0x + 1 or just y = 1.

I put together a short video tutorial which further illustrates this solution, and cited it as a source below. We hope it is helpful.

• Bob B
Lv 7
8 years ago

The line for the equation x = -2 is a vertical line that's drawn two units to the left of the y-axis.

A line perpendicular to that one must be horizontal.

A horizontal line passing through point (2, 1) has a constant y value of 1. Its equation is:

y = 1

• Brenda
Lv 7
8 years ago

because your line is x=-2 , which is a vertical line , then the perpendicular line to it has to be an horizontal line which means y=k

because the given point is (2,1) , then the line perpendicular to x=-2 is y=1

• 8 years ago

x = -2 is a vertical line so we want a horizontal line through (2, 1). That line is y = 1.