Question

If x-y=4 and day=45,find the value of x3-y3

Answer 1

$\huge\underline{\bold{\red{Answer}}}$ :


$\textbf{x - y = 4}$

$\textbf{xy = 45}$ (Day)

$\textbf{x}^{3}\:-\:{y}{^3}$ = $\textbf{?}$

(x - y)³ = x³ - y³ - 3xy (x - y)

(4)³ = x³ - y³ - 3 (45) (4)

64 = x³ - y³ - 540

x³ - y³ = 64 + 540

$\textbf\red{{x}^{3}\: - \:{y}^{3}}$ = $\textbf\red{604}$

Answer 2

$\bf{\underline{Answer}}$

Since, given that :-

x - y = 4

and , xy = 45 days

then , we have to find :

x³ - y³ = ?

so , we know that ,

(x - y)³ = x³ - y³ - 3xy (x - y)

using this identity ,

substitute the values given ,

=> (4)³ = x³ - y³ - 3 (45)(4)

Solve the terms,

=> 4 × 4 × 4 = x³ - y³ - 3 × 45 × 4

=> 64 = x³ - y³ - 540

take the like terms to RHS , i.e.,

=> x³ - y³ = 64 + 540

=> x³ - y³ = 604 ...answer

hence, answer is :-

$\boxed{\bold{{x}^{3} - {y}^{3} = 604}}$