Question

Evaluate (998)^3 by using the identity (a-b)^3 = a^3 - b^3 - 3ab (a-b)

Answer 1

Hey

Here is your answer,

By using the identity (a-b)^3 = a^3 - b^3 - 3ab (a-b),

998 can be written as (1000-2)

(1000-2)^3 = (1000)^3 - (2)^3 - 3 x 1000 x 2 (1000-2)

=1000000000 - 8 - 6000 (998)

=999999992 - 5988000

=999401198

Hope it helps you!

Answer 2

$\huge{\mathfrak{The\ answer\ is\ 994011992}}$

Step-by-step explanation:

So let 998 be 1000-2, it's gonna be easy to do so.

WKT,

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

Let a=1000 and b=2

$\bold{ {(1000 - 2)}^{3} = {1000}^{3} - {2}^{3} - 3 \times 1000 \times 2 \times (1000 - 2)} \\ \\ \bf 1000000000 - 8 - 6000 \times 998 \\ \\ \bf1000000000 - 8 - 5988000 \\ \\ \bf1000000000 - 5988008 \\ \\ \bf994011992$