For a quadratic equation ax2+bx+c=0, if a root is given, substitute it into the equation to find the unknowns. Calculation: Substituting the root 2 into the first equation: p(2)2+p(2)+4=0 ⇒4p+2p+4=0 ⇒6p+4=0 ⇒6p=−4 ⇒p=−
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Substituting the root 2 into the second equation: (2)2+q(2)+q=0 ⇒4+2q+q=0 ⇒4+3q=0 ⇒3q=−4 ⇒q=−
