Question

of the roots of the quadratic equation 2 X square + kx - 2 is equal to zero is minus 2 find k ​

Answer 1

Question -

If the roots of the quadratic equation 2x² + kx - 2 = 0 is -2, then find k.

$\LARGE{\bf{\underline{\underline{GIVEN:-}}}}$

• The quadratic equation 2x² + kx - 2 = 0 has a root -2.

$\LARGE{\bf{\underline{\underline{TO:FIND:-}}}}$

• The value of k.

$\LARGE{\bf{\underline{\underline{SOLUTION:-}}}}$

Concept - There will always be either one or two roots in a quadratic equation. We are given a root, i.e., -2. So, it can satisfy both sides of the equation. In other words, we can substitute x= -2:

$\sf{\red{x^2+kx-2=0}}$

▣ Substitute k = -2.

$\sf (-2)^2+k(-2)-2=0$

▣ This is a linear equation now! Continue to simplify and transpose the constants to one side.

$\to \sf 4-2k=-2$

$\sf \to k=\dfrac{-6}{-2}$

$\leadsto \boxed{\sf{\red{k=3}}}$

∴The value of k is 3.