(a+2)²-(a+3)² 2011²-2010² 17²+2×17+13²
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(a+2)²-(a+3)² 2011²-2010² 17²+2×17+13²
(a+2)²-(a+3)² 2011²-2010² 17²+2×17+13²
(a+2)²-(a+3)² 2011²-2010² 17²+2×17+13²
(a+2)²-(a+3)²
=(a+2+a+3)(a+2-a-3)
=-(2a+5)
2011²-2010²
=(2011-2010)(2011+2010)
=1*4021
=4021
17²+2×17×13+13²
=(17+13)²
=30²
=900
(a+2)²-(a+3)²
=[(a+2)+(a-3)][(a+2)-(a-3)]
=(2a-5)×5
=10a-25
2011²-2010²
=(2011+2010)(2011-2010)
=4021
17²+2×17×13+13²
=(17+13)²
=30²
=900