6. (a) In what ratio does the point [tex]\((x, 0)\)[/tex] divide the line joining the points [tex]\((4,12)\)[/tex] and [tex]\((-3,5)\)[/tex]? Hence, find the value of [tex]\(x\)[/tex].



Answer :

To determine the ratio in which the point [tex]\((x, 0)\)[/tex] divides the line segment joining the points [tex]\(A(4, 12)\)[/tex] and [tex]\(B(-3, 5)\)[/tex], as well as the corresponding [tex]\(x\)[/tex]-coordinate, we will follow these steps:

1. Find the ratio using the section formula:

The key idea is to use the section formula which states that if a point [tex]\(P(x, y)\)[/tex] divides the line joining [tex]\(A(x_1, y_1)\)[/tex] and [tex]\(B(x_2, y_2)\)[/tex] in the ratio [tex]\(m:n\)[/tex], then the coordinates of [tex]\(P\)[/tex] can be found using:

[tex]\[ P(x, y) = \left( \frac{m x_2 + n x_1}{m + n}, \frac{m y_2 + n y_1}{m + n} \right) \][/tex]

Since the point [tex]\(P\)[/tex] lies on the x-axis, its coordinates are [tex]\((x, 0)\)[/tex]. Therefore, the y-coordinate equation should satisfy:

[tex]\[ \frac{m y_2 + n y_1}{m + n} = 0 \][/tex]

Plugging in the coordinates of [tex]\(A\)[/tex] and [tex]\(B\)[/tex]:

[tex]\[ \frac{m \cdot 5 + n \cdot 12}{m + n} = 0 \][/tex]

Simplifying this equation:

[tex]\[ 5m + 12n = 0 \][/tex]

So:

[tex]\[ 12n = -5m \quad \Rightarrow \quad \frac{m}{n} = -\frac{12}{5} \][/tex]

This implies that the ratio [tex]\(m:n = -12:5\)[/tex].

2. Determine the x-coordinate:

Using the same section formula for the x-coordinate:

[tex]\[ x = \frac{m x_2 + n x_1}{m + n} \][/tex]

Substituting the values [tex]\(x_1 = 4\)[/tex], [tex]\(x_2 = -3\)[/tex], and the ratio [tex]\(m = -12\)[/tex], [tex]\(n = 5\)[/tex]:

[tex]\[ x = \frac{-12 \cdot (-3) + 5 \cdot 4}{-12 + 5} \][/tex]

Simplifying the numerator:

[tex]\[ -12 \cdot (-3) + 5 \cdot 4 = 36 + 20 = 56 \][/tex]

And the denominator:

[tex]\[ -12 + 5 = -7 \][/tex]

So the value of [tex]\(x\)[/tex] is:

[tex]\[ x = \frac{56}{-7} = -8 \][/tex]

Therefore, the point [tex]\((x, 0)\)[/tex] divides the line segment joining points [tex]\(A(4, 12)\)[/tex] and [tex]\(B(-3, 5)\)[/tex] in the ratio [tex]\(-12:5\)[/tex], and the value of [tex]\(x\)[/tex] is [tex]\(-8\)[/tex].