Question
For all positive integers x, let x▲ be defined to be (x-1)(x+1). Which of the following is equal to 6▲ - 5▲ ?
Does this mean I'm supposed to multiply the 6 and the 5 to (x^2-1) and subtract them from each other?
Does this mean I'm supposed to multiply the 6 and the 5 to (x^2-1) and subtract them from each other?
Answers
Reiny
x▲ = (x-1)(x+1)
then
6▲ - 5▲
= (6-1)(6+1) - (5-1)(5+1)
= 35 - 24
= 11
11 should be one of your choices
or the way you did it:
x▲ = (x-1)(x+1) = x^2 - 1
6▲ = 36-1 = 35
5▲ = 24-1 = 24
as above
then
6▲ - 5▲
= (6-1)(6+1) - (5-1)(5+1)
= 35 - 24
= 11
11 should be one of your choices
or the way you did it:
x▲ = (x-1)(x+1) = x^2 - 1
6▲ = 36-1 = 35
5▲ = 24-1 = 24
as above