Question

Using $(x+a)(x+b)=x^2+(a+b)x+ab$, find $103\times 104$.

• A. $14982$
• B. $11992$
• C. $10712$
• D. $11482$

Answer 1

The correct option is C $10712$

Given, $103\times 104$

$=(100+3)(100+4)$.

Using, $(x+a)(x+b)=x^2+(a+b)x+ab$.

Then,

$103\times 104$
$=(100+3)(100+4)$
$=(100{)}^2+(3+4\left)\right(100)+(3\left)\right(4)$

$=(100{)}^2+(7\left)\right(100)+12$
$=10000+700+12$

$=10712$.

Therefore, option $C$ is correct.