Porisma

A hint to get started

Recover the curve from its range and count line intersections

C:y=(−2x2−2x+a)/(x+1)C:y=(-2x^2-2x+a)/(x+1), where a is a non-zero constant. C exists for y≤−2 or y≥b, where b is positive.

(i) Using an analytical method, show a=−2 and hence find b. marks

(ii) Sketch C, clearly showing turning-point coordinates and asymptotes. marks

(iii) Show(−3,6) lies on y=px+3 p+6 for every real p. Hence use the sketch in(ii) to find p for which px+3p+6=(−2x2−2x−2)/(x+1)px+3p+6=(-2x^2-2x-2)/(x+1) has two distinct real roots. marks

[2015/SRJC/MYE/9]

CJC · Review problems · Question 9

The endpoints of the stated range become roots of the discriminant polynomial.

Read the worked solution