Factorize:
x^4 - 6x^2 - 27

x^4 - 6x^2 - 27

Let u = x^2

We know that x^4 = (x^2)^2.

u^2 - 6u - 27

(u - 9)(u + 3)

Now, back-substitite for u.

(x^2 - 9)(x^2 + 3)

The RIGHT SIDE FACTOR is the difference of two squares.

So, x^2 - 9 becomes (x - 3)(x + 3).

(x - 3)(x + 3)^2

Done.

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step-by-step explanation:

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walter needs to make at least 5 more cookies but no more than 40. 5 ≤ x ≤ 40

step-by-step explanation:

20 ≤ x + 15 ≤ 55

subtract 15 from all parts

20-15 ≤ x + 15-15 ≤ 55-15

5 ≤ x ≤ 40

this means how many more cookies he has to make

walter needs to make at least 5 more cookies, but no more than 40 cookies; 5 ≤ x ≤ 40