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Mathematics

If the point P(k, 0) divides the line segment joining the points A(2, -2) and B(-7, 4) in the ratio 1 : 2, then the value of k is:

  1. -2

  2. -1

  3. 1

  4. 2

Section Formula

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Answer

Given,

P = (k, 0)

m1 : m2 = 1 : 2

P(k, 0) divides the line segment joining the points A(2, -2) and B(-7, 4) in the ratio 1 : 2.

If the point P(k, 0) divides the line segment joining the points A(2, -2) and B(-7, 4) in the ratio 1 : 2, then the value of k is: Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = (m1x2+m2x1m1+m2,m1y2+m2y1m1+m2)\Big(\dfrac{m1x2 + m2x1}{m1 + m2}, \dfrac{m1y2 + m2y1}{m1 + m2}\Big)

Substituting values we get :

(k,0)=(1×(7)+2×21+2,1×4+2×(2)1+2)(k,0)=(7+43,443)(k,0)=(33,03)(k,0)=(1,0).\Rightarrow (k, 0) = \Big(\dfrac{1 \times (-7) + 2 \times 2}{1 + 2}, \dfrac{1 \times 4 + 2 \times (-2)}{1 + 2}\Big) \\[1em] \Rightarrow (k, 0) = \Big(\dfrac{-7 + 4}{3}, \dfrac{4 - 4}{3}\Big) \\[1em] \Rightarrow (k, 0) = \Big(\dfrac{-3}{3}, \dfrac{0}{3}\Big) \\[1em] \Rightarrow (k, 0) = (-1, 0).

Thus, k = -1.

Hence, Option 2 is the correct option.

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