Name: 多項式的零點：繪製零點｜多項式圖形｜代數2｜可汗學院 (Zeros of polynomials: plotting zeros | Polynomial graphs | Algebra 2 | Khan Academy)
Uploaded: 2021-01-14T10:14:26.000Z
Duration: 3 min 19 s
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- [Instructor] We're told we want to find the zeros

the polynomial right over here, and it's in factored form.

And so this is a screenshot from Khan Academy.

you would click where the zeros are to plot the zeros,

So pause this video and see if you could have a go

All right, now let's work on this together.

for what x values are p of x equal to zero?

hey, what x values would make two x times two x

'cause this is p of x, what x values would

Well, as we've talked about in previous videos,

if you take the product of things and that equals zero,

So for example, if two x is equal to zero,

that means x is equal to zero, and you could try that out.

If x is equal to zero, this part right over here is

Doesn't matter what these other two things are.

well, well maybe two x plus three is equal to zero,

and if that were true, what would x, or what would x

two x would have to be equal to negative three,

'cause if x is equal to negative 3/2, then two x plus three

is equal to zero, you take a zero times whatever this is

and whatever that is, you're gonna get zero.

That would make the whole product equal to zero.

So what x value makes x minus two equal zero?

doesn't matter what these other two things are.

So just like that, we have the zeros of our polynomial,

that's where it would intersect the x-axis,

Once again, if you're doing this on Khan Academy,

And then, we have x equals two, which is right over there.

because you could use it to graph a function.

I don't know exactly what this function looks like,

We would have to try out a few other values to get a sense

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多項式的零點：繪製零點｜多項式圖形｜代數2｜可汗學院 (Zeros of polynomials: plotting zeros | Polynomial graphs | Algebra 2 | Khan Academy)

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