for all integers r and s, let r#s=4r-3s. which of the following must be true?
I. 4#3=7
II. (1#0)#2=1#(0#2)
III. r#s=s#r

Question

for all integers r and s, let r#s=4r-3s. which of the following must be true?
I. 4#3=7
II. (1#0)#2=1#(0#2)
III. r#s=s#r

hartnn · Answer

r#s=4r-3s 

4#s
means r=4, s=3

= 4*4 - 3*3
is it = 7
?

anonymous · Answer

do you mean the answer is only I ?? @hartnn

hartnn · Answer

1 is true

i didn't check II. 
did u?

hartnn · Answer

III. is not true

hartnn · Answer

1#0 =4
4#2 = 10

0#2 =-6
1#-6 = 4+18 = 22

so II is not true

hartnn · Answer

only I is true...unless i did some careless calculation mistake :P
verify it...

anonymous · Answer

can i know whats the function of # ?

hartnn · Answer

its already defined!

$ r\#s=4r-3s $

hartnn · Answer

in words, 
"multiply first number by 4, 2nd number by 3 and take the difference"

anonymous · Answer

ohh i got it now thank you @hartnn

hartnn · Answer

welcome ^_^