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If a, b, c are in A.P. then the straight line ax + by + c = 0 will always pass through a fixed point whose coordinates are
  • a)
    (1, -2)
  • b)
    (-1, 2)
  • c)
    (1, 2)
  • d)
    (-1, -2)
Correct answer is option 'A'. Can you explain this answer?
Most Upvoted Answer
If a, b, c are in A.P. then the straight line ax + by + c = 0 will alw...
Given, a, b, c are in A.P.
Let the common difference be d.
So, b = a + d and c = a + 2d
Now consider the equation ax + by + c = 0
Substituting the values of b and c, we get
ax + (a + d)y + (a + 2d) = 0
Simplifying this equation, we get
y = -(a/d)x - (a+2d)/d
This is the equation of a straight line in slope-intercept form.
The slope of this line is -a/d, which is constant for any values of a and d.
So, the line will always pass through a fixed point whose coordinates are independent of the values of a and d.
To find this point, we can substitute any two values of a and d and solve for the point of intersection of the two lines.

Substituting a = 1 and d = 1, we get the equation of the first line as y = -x - 3.
Substituting a = 2 and d = 1, we get the equation of the second line as y = -2x - 4.
Solving these two equations, we get the point of intersection as (1, -2).

Hence, the fixed point through which the given line always passes is (1, -2).
Therefore, the correct answer is option A.
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Community Answer
If a, b, c are in A.P. then the straight line ax + by + c = 0 will alw...
Given, a, b, c are in A.P.

We know that in an A.P., the common difference (d) is a constant.

Let the common difference be d. Therefore, b = a + d and c = a + 2d.

The equation of the line passing through (x1, y1) and (x2, y2) is given by:

(y - y1)/(y2 - y1) = (x - x1)/(x2 - x1)

Let the fixed point be (x, y). Therefore, the equation of the line passing through (a, 1), (b, -2), and (c, 4) is:

(1 - y)/(-2 - y) = (a - x)/(b - x)
(-2 - y)/4-y = (b - x)/(c - x)

On solving the above two equations, we get:

x = (a + 2b + 2c)/5 and y = (-2a - b + 2c)/5

Therefore, the fixed point is (1, -2). Hence, option A is the correct answer.
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If a, b, c are in A.P. then the straight line ax + by + c = 0 will always pass through a fixed point whose coordinates area)(1, -2)b)(-1, 2)c)(1, 2)d)(-1, -2)Correct answer is option 'A'. Can you explain this answer?
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