The equation of the line passing through (1, 2) and perpendicular to x + y + 7 = 0 is

(A) y – x + 1 = 0 

(B) y – x – 1 = 0

(C) y – x + 2 = 0 

(D) y – x – 2 = 0.

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1 Answers

(B) is the correct answer. Let the slope of the line be m. Then, its equation passing through (1, 2) is given by

y – 2 = m (x – 1) .......(1)

Again, this line is perpendicular to the given line x + y + 7 = 0 whose slope is – 1

Therefore, we have m ( – 1) = – 1

or, m = 1

Hence, the required equation of the line is obtained by putting the value of m in (1), i.e.,

y – 2 = x – 1

or, y – x – 1 = 0

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