Question

The value of 'k' for which the quadratic equation 3x2-kx+7=0 has equal roots is _____

Answer 1

Let the equal roots be y

Then, we know that sum of roots = -b/a and product = c/a

→ 2y = k/3

→ y = k/6

and y² = 7/3

Put y = k/6 in second equation

→ k²/36 = 7/3

→ k² = 84

→ k = ±√84

Answer 2

Answer:

Answered by Rohith kumar. R..

☆Look at the discrimnant

☆For real roots ,D>0

k^2-4×3×7>0

k^2>84

k>root 84.

(or)

☆We can use quadratic equation

ax^2+bx+c=0

solved by

☆k=-b+/-root b^2-4ac

2

= a=3,b=-k, c=+7

(-k)^2-4×3×7

k^2-12×7

k^2-84=0

k^2=84

k= +/- 84.

☆Hope it helps u mate.

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☆Thank you.