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Quadratic Roots?
I had some test questions which i got wrong and i'm confused about why the answer is what it is.
Is 3 a root of this equation: y = (x - 3) · (x - 2)? the answer on the test is 'yes' and i dont understand how.
and
Find the roots of this equation: y = (x - 3) · (x + 1)
I think the answer is x = 3, 1 but the test says it is x = 3, -1
help with why they are what they are!?
show your work please!
Thanks!
2 Answers
- hayharbrLv 71 decade agoFavorite Answer
Actually it's called a zero not a root. It would be a root of the equation 0 = (x - 3) · (x - 2) because when you put 3 in for x the answer comes out zero
In the other it's -1 not 1 because (x+1) would equal 2 if x were 1. You want it to come out zero so use -1. The root always has the opposite sign of the number inside, if it starts with x.
- 1 decade ago
the roots are what will make the equation 0
so x-3 = 0 if x =3, similarly if X+1 = 0, x must be -1
Snce it's y=(x-3)(x-2) and if x-3 is 0, then it's y=(0)(x-2), which is 0.
