How to systematically enumerate all possibilities of +b)+c)+d)+e? i know that when (a+b)+c=a+(b+c) then to do ((a+b)+c)+d =(a+b)+(c+d) < --"counted" all possible outer brackets =(a+(b+c))+d < -- just "slide" the brackets off =a+((b+c)+d) a+(b+(c+d)) < -- by finish '"sliding" i should get the originals questions mirror image as a result.

step-by-step explanation:

assume that you have 3 different side lengths.   apply the pythagorean theorem here:   square each of the two shortest sides; call them a and b, so that their squares are a² and b².   also square the longest side, calling the result c².

now, if a² + b² = c² is true, the triangle is a right triangle; otherwise it is not a right triangle.

zero

step-by-step explanation:

f(2)= x-2

plug in the 2 in the "x"

f(2)=2-2

f(2)=0