Question

please please please solve it i am in difficult situation a-b=7 and ab=8 then find a^3-b^3?​

Answer 1

The value of  $a^{3}$ - $b^{3}$ is "511".

Step-by-step explanation:

Given

a - b = 7 and ab = 8

To find $a^{3}$ - $b^{3}$ = ?

We know that,

$(a - b)^{3}$  = $a^{3}$ - $b^{3}$ - 3ab(a-b)

∴ $a^{3}$ - $b^{3}$ = $(a - b)^{3}$ + 3ab(a-b)

Put a - b = 7 and ab = 8, we get

$a^{3}$ - $b^{3}$ = $(7)^{3}$ + 3 × 8 × 7

= 343 + 24 × 7

= 343 + 168

= 511

Hence, the value of  $a^{3}$ - $b^{3}$ is "511".