Page 29 - CHAPTER 4 (Quadratic equations)

CHAPTER 4
QUADRATIC EQUATIONS

19. The speed of a boat in still water is 15km/hr. It can go 30km

upstream and return downstream to the original point in 4 hours

30 minute. Find the speed of the stream.

20. A takes 6 days less than the time taken by B to finish a piece of work.

If both A and B together can finish it in 4 days, find the time taken

by B to finish the work.

21. Two numbers differ by 4, and their product is 192. The numbers are

(1) 12, 16 (2) 10, 14 (3) 11, 15 (4) 13, 18

22. If 2+i√3 is a root of the equation x²+px+q=0 where p and q are real,

then (p, q) =

(1) (–4, 7) (2) (4, –7) (3) (4, 7) (4) (–4, –7)

1
23. The values of x satisfying the equation is x-1 + x-3 =3 ;x≠2,4
x-2 x-4 3

3
5
9
7
(1) 3, (2) 5, (3) 7, (4) 9,
2 2 2 2
24. The quadratic equation whose roots are twice the roots of
2x²-5x+2=0 is

(1) 8x²-10x+2=0 (2) x²-5x+4=0

2
(3) 2x²-5x+2=0 (4) x -10x+6=0

25. If ≠ 0 and the equation = + has two equal roots, then p
2 + −
can be

(1) (√a-√b)² (2) (√a+√b)²

(3) a + b (4) a – b

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