Hey there :)
( a - b )( a² + ab + b² )
Let us distribute ( a - b ) into the other
a ( a² ) + a ( ab ) + a ( b² ) - b ( a² ) - b ( ab ) - b ( b² )
a³ + a²b + ab² - a²b - ab² - b³
We can further simplify
a²b - ab² = 0
ab² - ab² = 0
a³ - b³You can see in the picture which I have attached. It is the 8th formula
Make variables for each
L = library books
P = telephone books
T = text books
so.... L+P = 2T
now we have to fill in numbers
By definition, an obtuse triangle has an obtuse angle (angle greater than 90 degrees). The 3 angles of a triangle always add up to 180 degrees. Since one of our angles is greater than 90 degrees, the other 2 have to add up to less than 90 degrees, so there can be NO RIGHT ANGLES.
Percent change is (original-new)/(original), then multiply by 100