What is 3(u-16)+13=19 what does u equal

Step-by-step explanation:

x = length of screen

x-4 = width of screen

x² + (x-4)² = 20²

x² + (x²-8x+16) = 400

2x² - 8x - 384 =  0

x² - 4x - 192  = 0

use the quadratic formula to solve for x

x = [4 ± √(4²-4·1(-192))]/[2·1]

= [4 ± √784]/2

= 4 ±  28]/2

= 16, -12

-12 is an extraneous solution, so x = 16 inches.

Exponents need to be marked with a ^. For example, (x-4)² can be written (x-4)^2.