If (x + k ) is a factor of 2x² + 2kx + 5x + 10, find k.
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Answered by
30
(x+k) is a factor,hence at x=-k,the equation should become zero..
2k^2+2k(-k)-5k+10=0.........
2k^2-2k^2-5k=-10.......k=2
Answered by
110
If (x+k) is a factor then x = - k
Now , 2x²+2kx+5x+10 = 0 -----------------(1)
Now, substituting - k in the place of x in equation (1)
⇒2(-k)²+2k(-k)+5(-k)+10 = 0
⇒2k²-2k²-5k+10 = 0
⇒-5k=-10
⇒5k=10
⇒k=10/5
⇒k=2 .
Now , 2x²+2kx+5x+10 = 0 -----------------(1)
Now, substituting - k in the place of x in equation (1)
⇒2(-k)²+2k(-k)+5(-k)+10 = 0
⇒2k²-2k²-5k+10 = 0
⇒-5k=-10
⇒5k=10
⇒k=10/5
⇒k=2 .
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