Question

Find the value of x and y respectively.
$8^3$ - $7^3$ = 1 + x $\times$ y $\times$​ 3

• A. 8,7
• B. 8,6
• C. 7, 9
• D. 6,8

Answer 1

The correct option is A

8,7

$a^3$ – $b^3$ = $(a-b{)}^3$ + 3ab(a - b)​
​$8^3$ - $7^3$ = $(8-7{)}^3$ + 3 $\times$ 8 $\times$ 7 $\times$ (8 - 7) ---- (i)
$8^3$ - $7^3$ = 1 + x $\times$ y $\times$​ 3 ----(ii)
Comparing (i) and (ii), we get;
x = 8 and y = 7