How to use the discriminant to find out how many real number roots an equation has for $x^2 - 5x + 7 = 0$ ?

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Answer 1 · 2018-04-26T08:49:14

No real roots

$d=b^2-4ac$

If $d>0;"two real roots"$
If $d=0;"one distinct real roots"$
If $d<0;"no real roots"$

$d=(-5)^2-4(7)=25-28=-3$

$-3<0; "no real roots"$

How to use the discriminant to find out how many real number roots an equation has for x^2 - 5x + 7 = 0x^2 - 5x + 7 = 0?