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# What is the axis of symmetry of the function f(x) = -(x + 9)(x - 21)?

**Solution:**

It is given that

f(x) = -(x + 9)(x - 21)

Using the multiplicative distributive property

f(x) = -(x^{2} - 21x + 9x - 189)

f(x) = -x^{2} + 21x - 9x + 189

f(x) = -x^{2} + 12x + 189

We know that

Axis of symmetry x = -b/2a

Substituting the values

x = -12/ 2(-1)

x = -12/-2

x = 6

Therefore, the axis of symmetry is 6.

## What is the axis of symmetry of the function f(x) = -(x + 9)(x - 21)?

**Summary:**

The axis of symmetry of the function f(x) = -(x + 9)(x - 21) is 6.

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