[SOLVED]Algeb

Sudharaka

Well-known member
MHB Math Helper
srirahulan's question titled "Algeb" from Math Help Forum,

If $$ax^2+2x+1=0\mbox{ and }x^2+2x+a=0$$ have the common roots, find the real value of a.
Hi srirahulan,

Let $$\alpha\mbox{ and }\beta$$ be the two roots of these quadratic equations. Then, according to the first equation,

$\alpha+\beta=-\frac{2}{a}~~~~~~(1)$

Considering the second equation,

$\alpha+\beta=-2~~~~~~~(2)$

By (1) and (2);

$-\frac{2}{a}=-2$

$\therefore a=1$