123456789^2-2*123456789*123456787+123456787 = -15241578132906578 by copy and paste into web2.0 calculator
\(123456789^2-2*123456789*123456787+123456787\)
x=123456789
Rewrite this as:
x^2-2x(x-2)+x-2
(123456787 is 2 less that 123456789 so it can be written as x-2)
Now simplify the equation:
x^2-2x^2+4x+x-2 distribute -2x
-x^2+5x-2 combine like terms
That can't be factored so I guess that would be as simple as you can get it.
Doing the problem this way would be marginally more efficient, but I still wouldn't want to do that by hand. The problem looks like it is set up to be solved how I solved it, but the numbers didn't work out very well.
(123456789^2) - ((2*123456789*123456787)+123456787)
123456789^2 = 1524157 8750190521................................................................(1)
2*123456789*123456787+123456787 = 3048315 7130010673.......................(2)
Subtract (2) from (1):
15,241,578,750,190,521 - 30,483,157,130,010,673
=-15,241,578,379,820,152