# How do you evaluate (b-4)^ -2 for b=1 ?

Mar 16, 2016

$\frac{1}{9}$

#### Explanation:

color(blue)((b-4)^-2,color(orange)(b=1

Substitute the value of $b$

$\rightarrow {\left(1 - 4\right)}^{-} 2$

$\rightarrow {\left(- 3\right)}^{-} 2$

Remember the law of exponents color(brown)(x^-y=1/x^y

$\therefore {\left(- 3\right)}^{-} 2 = \frac{1}{- 3} ^ 2$

$\rightarrow = \frac{1}{\left(- 3\right) \left(- 3\right)}$

rArrcolor(green)(=1/9