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Mock Exam: June 22, 3H

The line [tex]\( y = 2x + p \)[/tex] and the circle [tex]\( x^2 + y^2 = 34 \)[/tex] intersect at points [tex]\( A \)[/tex] and [tex]\( B \)[/tex]. [tex]\( p \)[/tex] is a negative integer.

a) Show that the [tex]\( x \)[/tex]-coordinates of points [tex]\( A \)[/tex] and [tex]\( B \)[/tex] satisfy the equation:
[tex]\[ 5x^2 + 4xp + p^2 - 34 = 0 \][/tex]

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[tex]$5 / 8$[/tex] Marks
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[tex]$57 / 80$[/tex] Marks
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197 / 240 Marks
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5 & 6 & 7 \\
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Answer :

To show that the [tex]\( x \)[/tex]-coordinates of points [tex]\( A \)[/tex] and [tex]\( B \)[/tex] satisfy the equation [tex]\( 5x^2 + 4xp + p^2 - 34 = 0 \)[/tex], we need to follow a sequence of algebraic steps to derive this quadratic equation from the given equations of the line and the circle.

### Step-by-Step Solution:

1. Write the equations:
- The equation of the line is: [tex]\( y = 2x + p \)[/tex].
- The equation of the circle is: [tex]\( x^2 + y^2 = 34 \)[/tex].

2. Substitute the equation of the line into the equation of the circle:
- Since [tex]\( y = 2x + p \)[/tex], substitute [tex]\( y \)[/tex] in the circle's equation:
[tex]\[ x^2 + (2x + p)^2 = 34 \][/tex]

3. Expand the substituted equation:
- Expand [tex]\( (2x + p)^2 \)[/tex]:
[tex]\[ (2x + p)^2 = 4x^2 + 4xp + p^2 \][/tex]
- Now substitute back into the circle's equation:
[tex]\[ x^2 + 4x^2 + 4xp + p^2 = 34 \][/tex]

4. Combine like terms:
- Combine all the terms on one side of the equation to set it to 0:
[tex]\[ 5x^2 + 4xp + p^2 - 34 = 0 \][/tex]

Thus, we have successfully shown that the [tex]\( x \)[/tex]-coordinates of the points [tex]\( A \)[/tex] and [tex]\( B \)[/tex] satisfy the equation:
[tex]\[ 5x^2 + 4xp + p^2 - 34 = 0 \][/tex]

This completes the demonstration.