Write the equation of the line that is perpendicular to 10x=-y and passes through point (4,2/5)

To find the equation of a line perpendicular to the given line, we need to find the slope of the given line first.

Rewriting the given equation in slope-intercept form (y = mx + b), we have:
10x = -y
Rewriting as -y = 10x, we have:
y = -10x

Comparing this with the slope-intercept form, we see that the slope (m) is -10.

Since the line we want is perpendicular to this line, its slope will be the negative reciprocal of -10, which is 1/10.

Now, we have the slope (m) and a point (4, 2/5). We can use the point-slope form of a line to find the equation.

The point-slope form is given by:
y - y₁ = m(x - x₁)

Plugging in the values, the equation becomes:
y - (2/5) = (1/10)(x - 4)

Multiplying through by 10 to eliminate fractions, we have:
10y - 4 = x - 4

Rearranging the terms, we get:
x - 10y = 0

So, the equation of the line that is perpendicular to 10x = -y and passes through the point (4, 2/5) is x - 10y = 0.

To find the equation of a line that is perpendicular to a given line, we need to determine the slope of the given line and then find the negative reciprocal of that slope.

Let's start by rewriting the given equation in slope-intercept form (y = mx + b), where m represents the slope:

10x = -y

Dividing both sides of the equation by -1, we get:

-10x = y

Now, in slope-intercept form, the equation becomes:

y = -10x

We can see that the slope of the given line is -10.

The negative reciprocal of -10 is 1/10. So, the slope of the perpendicular line will be 1/10.

Now, let's use the point-slope form of a line to find the equation. The formula is given as:

y - y1 = m(x - x1),

where (x1, y1) represents the coordinates of the given point and m is the slope.

Substituting the values into the equation:

y - 2/5 = (1/10)(x - 4)

Simplifying:

y - 2/5 = (1/10)x - 4/10

y - 2/5 = (1/10)x - 2/5

Adding 2/5 to both sides:

y = (1/10)x - 2/5 + 2/5

y = (1/10)x

Therefore, the equation of the line that is perpendicular to 10x = -y and passes through the point (4, 2/5) is y = (1/10)x.