Question

If a-b = 1 and a3- b3 = 61 then the value of ab is. ( step by step explanation)​

Answer 1

Answer:

20

Step-by-step explanation:

a-b=1

a3-b3=61

let a=3 & b=2

(3)3-(2)3=27-8=19 is not equal to 61

let a=4 &b=3

(4)3-(3)3=64-9=53 is not equal to 61

let a=5 &b=4

(5)3-(4)3=125-64=61

so a=5 &b=4

so AB=5*4=20

Answer 2

Step-by-step explanation:

a3 - b3 = (a-b)^3 3ab(a-b)

61= (61)^3 + 3ab 61)

61 = 226981 + 3ab (61)

226981 - 61 = -3ab (61)

226920 = 183 ab

ab = 226920/183

ab=1240