Question

Simplify: (0.8m + 1.1n) (0.8m - 1.1n)

• A. $0.64m^2+1.12n^2$
• B. $0.64m^2+1.21n^2$
• C. $0.64m^2-1.21n^2$
• D. $0.64m^2-11.2n^2$

Answer 1

The correct option is C $0.64m^2-1.21n^2$

$(0.8m+1.1n)(0.8m-1.1n)$
$=(0.8m{)}^2-(1.1n{)}^2$
$=0.64m^2-1.21n^2$
[Using identity $a^2-b^2=(a+b)(a-b)$]