Question

6. If one root of the equation 2x2

+kx-6=0 is 2 then the value of „k‟ is=_____

A.1 B.-1 C.2 D.​

Answer 1

Answer:

In this question value of x is 2. so, 2*2+K(2)-6=0

4+2k-6=0

2k=2

k=1

Answer 2

$\bigstar \large \purple{ \pmb {\underline{ \sf question ...}}}$

• if one root of the equation $\sf2x²+kx-6$ is 0 then find the value of k.

$\bigstar \large \purple{ \pmb {\underline{ \sf Concept ...}}}$

• in this Question, we are already given the root of the equation which means we have the value of x
• by putting given root in equation and equating it with 0 we can find the value of k.

$\bigstar \large \purple{ \pmb {\underline{ \sf solution ...}}}$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: : \implies \sf 2 {x}^{2} + kx - 6 = 0$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: : \implies \sf 2 {(2)}^{2} + k(2)- 6 = 0$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: : \implies \sf 8 + 2k- 6 = 0$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: : \implies \sf 2 + 2k = 0$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: : \implies \sf 2k = - 2$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: : \implies \sf k = \dfrac{ \cancel{- 2}}{ \cancel2} = \red{ - 1}$

So, -1 is required value of k