If $81$ is discriminant of $2 x^{2} + 5 x - k = 0$ then the value of $k$ is

5

No worries! We‘ve got your back. Try BYJU‘S free classes today!

7

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

- 7

No worries! We‘ve got your back. Try BYJU‘S free classes today!

2

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is A $7$
the given equation $2 x^{2} + 5 x - k = 0$ is in the form of $a x^{2} + b x + c$

By comparing $a = 2, b = 5, c = - k$

Given, Descriminant $D = 81$ $(D = b^{2} - 4 a c)$

By equating,
$\Rightarrow b^{2} - 4 a c = 81$

$\Rightarrow 25 + 8 k = 81$

$\Rightarrow 8 k = 81 - 25$

$\Rightarrow 8 k = 56$

$\Rightarrow k = 7$

Suggest Corrections

Similar questions

3 x^{2} - 14 x + k = 0

100

k =

\sqrt{2} x^{2} - 5 x + \sqrt{2} = 0

(3 x + 14 y + 7) + k (5 x + 7 y + 6) = 0

k

- \frac{1}{2}

p (x) = 2 x^{2} - 5 x - k

k

If the line
$(3 x + 14 y + 7) + k (5 x + 7 y + 6) = 0$
is parallel to the y-axis, then the value of $k$ is

Join BYJU'S Learning Program