Question

x^3-3x^2-9x-5 factorise​

Answer 1

Answer:(x-5)(X+1)^2

Step-by-step explanation

When we equate the given polynomial to zero, we can see that when X=-1 the polynomial is equal to zero.

SO X+1 IS A FACTOR BY FACTOR THEOREM.

Now divide the polynomial by x+1, or group it to a simpler form.

X^3-3X^2-9X-5 = x^2(X+1) -4x(X+1) - 5(X+1)

= (X+1)(x^2-5x+x-5) by splitting the middle terms

=(X+1)(X(x-5)+1(x-5))

(X+1)(x-5)(X+1)

=(X-5)(X+1)^2