Question

Factorise $100-x^2$

• A. $x^2+2x+50$
• B. $(x+20)(x-5)$
• C. $(x+10)(10-x)$
• D. $x^3-12x+50$

Answer 1

The correct option is C $(x+10)(10-x)$

$100-x^2$
We know $a^2-b^2=(a+b)(a-b)$
a = 10 and b = x ; we have
${10}^2-x^2=(10+x)(10-x)$