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NDA (Held On: 18 Apr 2021) Maths Previous Year paper

Option 3 : pq - 1 = 0

Electric charges and coulomb's law (Basic)

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10 Questions
10 Marks
10 Mins

**Concept:**

Slope intercept form of a straight line ⇔ y = mx + c

Where m is the slope and c is the y-intercept

When two lines are perpendicular, the product of their slope is -1. If m is the slope of a line, then the slope of a line perpendicular to it is -1/m.

**Calculation:**

Given equations are, y + px = 1 and y - qx = 2 which can be written as,

y = - px + 1 and y = qx + 2

So, m_{1} (slope of 1st line)= -p and m_{2} (slope of 2nd line)= q

As they are perpendicular m_{1} × m_{2} = - 1

⇒ - pq = - 1

⇒ pq - 1 = 0