A line passing through P (-2,3) meets the axes in A and B. If P divides AB in the ratio 3: 4. then the
equation of the line is
(A) 5x - 2y - 20 = 0 (B) 2x - y + 7 = 0 (C) x - 3y - 5 = 0 (D) 2x + y - 4 = 0
Step by step answer please.
Answers
Given :-
- A line passing through P (-2,3) meets the axes in A and B. If P divides AB in the ratio 3: 4.
To Find :-
The equation of the line is :-
(A) 5x - 2y - 20 = 0
(B) 2x - y + 7 = 0
(C) x - 3y - 5 = 0
(D) 2x + y - 4 = 0
Solution :-
we know that, point slop form of equation of a line is :-
- (y - y1) = m(x - x1)
Given that, line passes through P(-2, 3).
So,
→ y - 3 = m(x - (-2))
→ y - 3 = m(x + 2)
it is also said that, the line meets the axes in A and B. .
So ,
→ At x - intercept , y = 0
→ 0 - 3 = m(x + 2)
→ -3 = mx + 2m
→ mx = (-3) - (2m)
dividing both sides by m,
→ x = (-3/m) - 2
Therefore,
→ co - ordinate at x - intercept = {(-3/m) - 2} , 0
Similarly,
→ At y - intercept , x = 0.
→ y - 3 = m(0 + 2)
→ y - 3 = 2m
→ y = (2m + 3)
Therefore,
→ co - ordinate at y - intercept = (0, 2m + 3)
Now,
we know that :-
- section formula says that the coordinates of a point which divides the line joining two points (a,b) and (c,d) in the ratio m : n is given by = P ( x , y ) = (cm + an)/(m + n) , (dm + bn)/(m + n) .
we have now :-
- x = (-2)
- y = 3
- a = {(-3/m) - 2}
- b = 0
- c = 0
- d = 2m + 3
- m = 3
- n = 4
Putting all values we get :-
→ (-2) = [0*3 + {(-3/m) - 2}*4] / (3 + 4)
→ (-2) * 7 = 0 + 4{(-3/m) - 2}
→ (-14) = (-12/m) - 8
→ (-14) + 8 = (-12/m)
→ (-6) = (-12)/m
→ m = (-12)/(-6)
→ m = 2.
Hence,
Equation of line :-
→ y - 3 = m(x + 2)
→ y - 3 = 2(x + 2)
→ y - 3 = 2x + 4
→ y - 3 - 4 = 2x
→ y - 7 = 2x
→ 2x - y + 7 = 0 (Option B) (Ans.)
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