Question

Using a suitable identity,find the value of $(98{)}^3$

Answer 1

$(98{)}^3$

$(100-2{)}^3$

$\therefore (a-b{)}^3=a^3-b^3-3a^{2}b+3a{b}^2$

$(100-2{)}^3=(100{)}^3-(2{)}^3-3\times (100{)}^2\times 2+3\times 100\times 2^2$

$=1000000-3-60000+1200$

$=941192$.