Question

Which of the following quadratic equations has roots 3, 5?
(A) x2 – 15x + 8 = 0 (B) x2 – 8x + 15 = 0
(C) x2 + 3x + 5 = 0 (D) x2 + 8x – 15 = 0

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Answer 1

option B

the basic concept of quadratic equations is ...the middle one is the summation of roots and last part is the product of roots.

3+5=8 and 3*5=15

so ONLY options left are Option B and Option D.

here is the catch ...if you notice in option D, the product is negetive. but as per our desired roots, positive product i.e., 15 is required

so option B is right answer.

note:- there is a method to know nature of roots for all 4 type quadratic equations.but I cannot elaborate it here. you can get that in youtube videos.

Answer 2

Answer:

got it ......................