Question

6.
5. The value of k for which the quadratic equation x - kx +4=0 have equal roots:
(a) 4,-4 (b) 16
(C) - 4
(d) 4
The sum of three consecutive terms of an increasing A.P. is 51 and the product of 1st
and 3rd of these terms is 273 then the third term is:
(a) 13
(b) 9
(c) 21
(d) 17
If (k+ 1) = sec 0 (1 + sin 0) (1 - sin o), find k.
8. If (cosec 0 + cot ) = x find cosec 0-cot .
7.
9.
If a pole 6 m high casts a shadow of 2/3 long on the ground then what is the sun's
elevation?​

Answer 1

Answer:

Given: polynomial x

2

−kx+4=0, has equal real roots

To find the value of k

sol: A quadratic equation has equal real roots if the discriminant b

2

−4ac=0

x

2

−kx+4=0 is of form ax

2

+bx+c=0

∴a=1,b=−k,c=4

Hence th discriminant is

(−k)

2

−4(1)(4)=0

⟹k

2

−16=0

⟹k

2

=16

Therefore, k=±4

Answer 2

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