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If roots of the equation $x^{2}-b x+c=0$ be two consecutive integers, then $b^{2}-4 c$ equals

1) $-2$
2) 3
3) 2
4) 1
| 41 views

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(4)

Explanation

Let $\alpha, \alpha+1$ be roots
$\alpha+\alpha+1=b$
$\alpha(\alpha+1)=c$
$\therefore b^{2}-4 c=(2 \alpha+1)^{2}-4 \alpha(\alpha+1)=1 .$

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