Question

. If * and # are two operations such that a*b=a+b+2 and a # b=a×b-4, find
a) (3*4) # 5
b) 3*(4#5)
c) Are they equal?

Answer 1

Answer:

a) (3*4)#5

(3*4)#5= (3+4+2)#5

=9×5-4

=41

b) 3*(4#5)

3*(4#5)=3* (4×5-4)

= 3+ 16 +2

=21

c) they are not equal

Answer 2

Answer:

• ( 3 * 4 ) # 5

(3+4+2) # 5 a*b = a+b+2

9 # 5

9 × 5 - 4 a#b = a×b-4

45 - 4 = 41

• 3 * (4 # 5)

3 * (4 × 5 - 4)

3 * (20 - 4)

3 * 16

3 + 16 + 2 = 21

• No they aren't equal