Find all numbers for which the rational expression is undefined

{-3, 8}

Step-by-step explanation:

This rational expression is undefined wherever the denominator is 0.

Thus, our task is to determine the roots of x² - 5x - 24:

This expression factors as follows:  (x - 8)(x + 3) = 0

Setting x - 8 = 0 and solving for x yields x = 8.

Similarly, x + 3 = 0 yields x = -3.  

This rational expression is undefined for {-3, 8}.

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.