=b^2-(4a^2-4a+ 1)

=b^2-(2a- 1)^2

=(b+2a- 1)(b-2a+ 1)

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2x^2- 18=2(x^2-9)=2(x+3)(x-3)

1/3x^2-2x+3= 1/3(x^2-6x+9)= 1/3(x-3)^2

So the common factor of 2x 2- 18, 1/3x 2-2x+3 is x-3.

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5100/5 99-51kloc-0/= a number you don't want to know.

But if the topic is

5^ 100/(5^99-5^ 10 1)

=5^ 100/5^99( 1-5^2)

=5*(-24)

=- 120

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x^2+y^2/2-xy

= 1/2(2x^2+y^2-2xy)

= 1/2(x^2+x^2-2xy+y^2)

= 1/2[x^2+(x-y)^2]

When x = 25 and y = 15.

= 1/2[625+(25- 15)^2]

= 1/2(625+ 100)

=725/2

=362.5