Mathematics
Given that 2 is a root of the equation 3x2 - p(x + 1) = 0 and that the equation px2 - qx + 9 = 0 has equal roots, find the values of p and q.
Quadratic Equations
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Answer
Since, 2 is the root hence, it satisfies the equation 3x2 - p(x + 1) = 0.
⇒ 3(2)2 - p(2 + 1) = 0
⇒ 3(4) - 3p = 0
⇒ 3p = 12
⇒ p = 4.
Substituting value of p in px2 - qx + 9 = 0
⇒ 4x2 - qx + 9 = 0
Comparing 4x2 - qx + 9 = 0 with ax2 + bx + c = 0 we get,
a = 4, b = -q and c = 9.
Since equation has equal roots,
∴ D = 0
⇒ (-q)2 - 4.(4).(9) = 0
⇒ q2 - 144 = 0
⇒ q2 = 144
⇒ q = 12 or -12.
Hence, p = 4 and q = 12 or -12.
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