Question

If Δ is an operation such that for integers a, b and c we have a Δ b Δ c = (ab + bc) – (b + c) × c, then find the value of (25) Δ (25) Δ (-5).

• A. 400
• B. 600
• C. -400
• D. -600

Answer 1

The correct option is B 600

It is given that
$a\Delta b\Delta c=(ab+bc)–(b+c)\times c$
So, the value of $\left(25\right)\Delta \left(25\right)\Delta (-5)$ can be calculated as follows:
$\left(25\right)\Delta \left(25\right)\Delta (-5)$
$=(25\times 25)+[25\times (-5\left)\right]–[25+(-5\left)\right]\times (-5)$
By applying distributive property we can re-write it as
$=25\times [25+(-5\left)\right]–[25+(-5\left)\right]\times (-5)$
$=25\times 20-20\times (-5)$
Again by applying distributive property we can re-write it as:
$=20\times (25+5)$
$=20\times 30$
$=600$