Find the equation of the line through the intersection of the lines 5x – 3y = 1 and 2x + 3y = 23 and which is perpendicular to the line 5x – 3y = 1.
Suppose the given two lines intersect at a point P(x1, y1). Then, (x1, y1) satisfies each of the given equations.
5x – 3y = 1 …(i)
2x + 3y = 23 …(ii)
Now, we find the point of intersection of eq. (i) and (ii)
Adding eq. (i) and (ii) we get
5x – 3y + 2x + 3y = 1 + 23
⇒ 7x = 24
Putting the value of x in eq. (i), we get
Hence, the point of intersection P(x1, y1) is
Now, we know that, when two lines are perpendicular, then the product of their slope is equal to -1
m1 × m2 = -1
⇒ Slope of the given line × Slope of the perpendicular line = -1
Slope of the perpendicular line
⇒The slope of the perpendicular line
So, the slope of a line which is perpendicular to the given line is
Then the equation of the line passing through the point having slope
y – y1 = m (x – x1)
⇒ 63x + 105y – 781 = 0