1.5 The equation of the horizontal line through the point [tex]\( A(-3, -5) \)[/tex] is [tex]\( y = -5 \)[/tex].

1.6 The equation of the vertical line through the point [tex]\( B(7, -8) \)[/tex] is [tex]\( x = 7 \)[/tex].

1.7 The gradient of the line defined by [tex]\( y + 5x + 7 = 0 \)[/tex] is [tex]\( -5 \)[/tex].

1.8 The gradient of the line defined by [tex]\( 3y - 9x + 12 = 0 \)[/tex] is [tex]\( 3 \)[/tex].

[8]

QUESTION 5

5.1 The gradient of the points [tex]\( P (5, a) \)[/tex] and [tex]\( Q (3, 4) \)[/tex] is [tex]\( -\frac{3}{2} \)[/tex]. Calculate [tex]\( a \)[/tex].

5.2 The gradient of the points [tex]\( M(x, 5) \)[/tex] and [tex]\( N(-3, 4) \)[/tex] is [tex]\( -\frac{1}{4} \)[/tex]. Calculate [tex]\( x \)[/tex].

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PSIS MATHEMATICS GRADE 9



Answer :

Let's break down and solve each part of the problem step by step.

### Question 5.1

Given:
- Point [tex]\( P(5, a) \)[/tex]
- Point [tex]\( Q(3, 4) \)[/tex]
- Gradient (slope) of line [tex]\( PQ = -\frac{3}{2} \)[/tex]

We use the formula for the gradient (slope) of a line passing through two points [tex]\((x_1, y_1)\)[/tex] and [tex]\((x_2, y_2)\)[/tex]:

[tex]\[ \text{Gradient} = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]

Substitute the given values:

[tex]\[ -\frac{3}{2} = \frac{4 - a}{3 - 5} \][/tex]

Simplify the denominator:

[tex]\[ -\frac{3}{2} = \frac{4 - a}{-2} \][/tex]

To eliminate the fraction, multiply both sides by [tex]\(-2\)[/tex]:

[tex]\[ -2 \times -\frac{3}{2} = 4 - a \][/tex]

This simplifies to:

[tex]\[ 3 = 4 - a \][/tex]

Solving for [tex]\( a \)[/tex]:

[tex]\[ a = 4 - 3 \][/tex]
[tex]\[ a = 1 \][/tex]

Thus, the value of [tex]\( a \)[/tex] is:

[tex]\[ a = 1 \][/tex]

### Question 5.2

Given:
- Point [tex]\( M(x, 5) \)[/tex]
- Point [tex]\( N(-3, 4) \)[/tex]
- Gradient (slope) of line [tex]\( MN = -\frac{1}{4} \)[/tex]

We use the same gradient formula for the line passing through points [tex]\( M \)[/tex] and [tex]\( N \)[/tex]:

[tex]\[ \text{Gradient} = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]

Substitute the given values:

[tex]\[ -\frac{1}{4} = \frac{4 - 5}{-3 - x} \][/tex]

Simplify the numerator:

[tex]\[ -\frac{1}{4} = \frac{-1}{-3 - x} \][/tex]

To eliminate the fraction, we can set up the equation and cross-multiply:

[tex]\[ -1 \times 4 = -1 \times (-3 - x) \][/tex]

Simplify both sides:

[tex]\[ -4 = 3 + x \][/tex]

Solving for [tex]\( x \)[/tex]:

[tex]\[ x = -4 - 3 \][/tex]
[tex]\[ x = -7 \][/tex]

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

[tex]\[ x = -7 \][/tex]

### Summary
- 5.1 The value of [tex]\( a \)[/tex] is [tex]\( 1 \)[/tex].
- 5.2 The value of [tex]\( x \)[/tex] is [tex]\( -7 \)[/tex].