If x1+x2=-b/a and x1*x2=c/a: how can i do x1-x2



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Posted on (Answer #1)

We have `x_1+x_2=-b/a` and `x_1*x_2=c/a`

`(x_1-x_2)` have to be found out.

we know, `(x_1-x_2)^2`

=`x_1^2-2*x_1*x_2+x_2^2 `

= `(x_1+x_2)^2-4*x_1*x_2` [as `(x_1+x_2)^2=x_1^2+2*x_1*x_2+x_2^2` ]

Putting the values of `(x_1-x_2)` and `x_1*x_2` we get,


= `b^2/a^2-4c/a`


`(x_1-x_2) = +-sqrt(b^2-4*a*c)/a`


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