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Chapter 3

Optional Mathematics

+2 college entrance (after SEE) past exam questions

Past questions and answers

2 questions set from this chapter. Most repeated first.

  • 2078

What is the inverse of the function? f(x)=2x−1f(x)=2x-1 (a) x−12\frac{x-1}{2} (b) 2x+12\frac{2x+1}{2} (c) 2x−12\frac{2x-1}{2} (d) x+12\frac{x+1}{2}

Answer

(d) x+12\frac{x+1}{2}

Let y=2x−1y=2x-1. Then x=y+12x=\frac{y+1}{2}, so f−1(x)=x+12f^{-1}(x)=\frac{x+1}{2}.

Check: f(x+12)=2⋅x+12−1=xf\left(\frac{x+1}{2}\right)=2\cdot\frac{x+1}{2}-1=x.

Answer checked by Claude Sonnet · Oct 21, 2026

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  • 2078

Reflection of the point P(x,y)P(x,y) about yy axis is (a) (y,x)(y,x) (b) (−y,x)(-y,x) (c) (−y,−x)(-y,-x) (d) (−x,y)(-x,y)

Answer

(d) (−x,y)(-x,y)

A reflection about the yy-axis changes the sign of the xx-coordinate and keeps the yy-coordinate, so P(x,y)→P′(−x,y)P(x,y)\to P'(-x,y).

Answer checked by Claude Sonnet · Oct 21, 2026

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Questions from Prasadi Entrance Test 2078, +2 Science (Prasadi Academy published entrance test paper (model/sample), 2078 BS). Answers are written for this site; check them against your class notes.