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If the equation x^(2)+2(k+2)x+9k=0 has e...

If the equation `x^(2)+2(k+2)x+9k=0` has equal roots then k= ?

A

1 or 4

B

`-1" or "4`

C

1 or -4

D

`-1" or "-4`

Text Solution

Verified by Experts

The correct Answer is:
A
Since the roots are equal, we have D=0.
`:." "4(k+2)^(2)-36k=0implies(k+2)^(2)-9k=0`
`:." "k^(2)-5k+4=0impliesk^(2)-4k-k+4=0impliesk(k-4)-(k-4)=0`
`implies(k-4)(k-1)=0impliesk=4" or "k=1.`
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RS AGGARWAL-QUADRATIC EQUATIONS -Test Yourself
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  2. If the equation 9x^(2)+6kx+4=0 has equal roots then k=?

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  3. If the equation x^(2)+2(k+2)x+9k=0 has equal roots then k= ?

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  4. If the equation 4x^(2)-3kx+1=0 has equal roots then k=?

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