Question

Using identities, evaluate:
$10.5\times 9.5$.

• A. 99.75
• B. 0.9975
• C. 9975
• D. 9.975

Answer 1

The correct option is A

99.75

We can write the given expresssion as,
$10.5\times 9.5=(10+0.5)(10-0.5)$

Using the identity:
$\left[\right(a+b\left)\right(a-b)=a^2-b^2]$
$=\left[\right(10{)}^2-\left(0.5{)}^2\right]$
$=100-0.25$
$=99.75$

Hence, the evaluation of $10.5\times 9.5is\mathrm{99.75.}$