(-3, 1) y = 2/5x - 4
x₁ y₁ slope (m) = 2/5x
Since the equation we are looking for is perpendicular to y = 2/5x - 4, we need to find the opposite reciprocal slope. We have to flip the slope upside down and turn it negative.
2/5 ⇒ 5/2 ⇒ -5/2
So far, we have the equation y = -5/2.
Now, we need to find the y intercept by plugging in the given point into point slope form, which is...
y - y₁ = m(x - x₁)
The subscripts in the y and x are just the x and y in (-3,1). They are just placeholders, not exponents.
y - 1 = -5/2(x + 3)
y - 1 = -5/2x - 15/2
+ 1 + 1
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y = -5/2x - 13/2 ⇒ final equation