In what ratio is the segment joining (−1,−12) and (3,4) divided by the x-axis?
- A1:3
- B3:2
- C3:1
- D2:3
Solution & Step-by-step Explanation
Let the x-axis divide the line segment joining A(−1,−12) and B(3,4) at point P(x,0) in the ratio k:1.
On the x-axis, the y-coordinate of any point is always 0.
Using the section formula for the y-coordinate:
y=
k+1
k⋅y
2
+1⋅y
1
Here, y
1
=−12, y
2
=4, and y=0:
0=
k+1
k(4)+1(−12)
0=4k−12
4k=12
k=3
Hence, the ratio k:1 is 3:1.
On the x-axis, the y-coordinate of any point is always 0.
Using the section formula for the y-coordinate:
y=
k+1
k⋅y
2
+1⋅y
1
Here, y
1
=−12, y
2
=4, and y=0:
0=
k+1
k(4)+1(−12)
0=4k−12
4k=12
k=3
Hence, the ratio k:1 is 3:1.