A^2 + b^2 = c^2...a and b are the legs and c is the hypotenuse
20^2 + 21^2 = c^2
400 + 441 = c^2
841 = c^2
sqrt 841 = c
29 = c <== third straw will be 29 cm

3 0

3 years ago

If f(x) =69-15x then f(f^-1(x))

xenn [34]

If f(x)=69-15x then $f(f^{-1}(x))=x$

Given :

$f(x)=69-15x\\$

Lets find out $f^{-1}(x)$ . The steps to find out f inverse are

Replace f(x) by y

$y=69-15x\\Interchange \; the \; variables\\x=69-15y\\solve \; for \; y\\x-69=-15y\\Divide \; by \; -15\\\frac{-x+69}{15} =y\\Replace \;y \;with \; f^{-1}\\f^{-1}=\frac{-x+69}{15}$

Now we find $f(f^{-1}(x))$

Replace inverse function in the place of x in f(x)

$f(f^{-1}(x))=f(\frac{-x+69}{15} )=69-15(\frac{-x+69}{15})=69-(-x+69)=69+x-69=x\\f(f^{-1}(x))=x$

Learn more :

brainly.com/question/11242094

8 0

3 years ago