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Question
If 1 and –2 are the roots of the equation x3 – 4x2 – px + r=0, then its third root will be
If 1 and –2 are the roots of the equation x3 – 4x2 – px + r=0, then its third root will be
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Solution
The correct option is D 5
For the equation x3 – 4x2 – px + r=0, two roots are 1 and -2.
Let the third root be 'p'.
Sum of roots = − −41∴1+(−2)+p=4⇒−1+p=4⇒p=5
For the equation x3 – 4x2 – px + r=0, two roots are 1 and -2.
Let the third root be 'p'.
Sum of roots = − −41∴1+(−2)+p=4⇒−1+p=4⇒p=5