If one of the roots of the quadratic equation 2x 2 +px+4=0 is 2, then the…
2018
If one of the roots of the quadratic equation 2x 2 +px+4=0 is 2, then the other root is:
- A.
-2
- B.
-1
- C.
+1
- D.
+2
Attempted by 48 students.
Show answer & explanation
Correct answer: C
Key idea: For a quadratic equation ax^2 + bx + c = 0, the product of the roots equals c/a.
Here a = 2 and c = 4, so product of the roots = 4/2 = 2.
Let the other root be r. Then 2 × r = 2, which gives r = 1.
Therefore the other root is 1.