Question

1.Using factor theorem show that (a-b) is the factor of a(b^2-c^2)+b(c^2-a^2)+c(a^2-b^2)

Answer 1

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Answer 2

Consider a polynomial f (x) which is divided by (x – c) .

Then, f (c) = 0.

Thus, by the Remainder theorem,

Thus, (x – c) is a factor of the polynomial f (x).

Proof of the converse part:

By the Remainder theorem,

f (x) = (x – c) q(x) + f (c)

If (x – c) is a factor of f (x), then the remainder must be zero.

That is, (x – c) exactly divides f (x).

Thus, f (c) = 0.

Hence proved.

Note:

The Remainder theorem says, if (x - c) divides the polynomial f (x), then the remainder is f (c) That is,

f (x) = (x – c) q(x) + f (c)

Suppose the remainder f (c) = 0, f (x) = (x – c) q(x).

Thus, (x – c) is the factor of f (x). Hence, it can be concluded that the “Factor theorem” is the reverse of “Remainder theorem”.

Example:

Consider a polynomial. Determine whether (x+1) is a factor of f (x).

By the Factor theorem, (x + 1) is a factor of f (x) if f (–1) = 0.

Obtain the value of f (–1).

Since f (–1) = 0, (x + 1) is a factor of f (x).