Toán Lớp 7: Tại sao a^2 + b^2 – 2ab = ( a – b )^2
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Toán Lớp 7: Tại sao a^2 + b^2 – 2ab = ( a – b )^2
Comments ( 2 )
a^2+b^2-2ab
=a^2-2ab+b^2
=a^2-(ab+ab)+b^2
=a^2-ab-ab+b^2
=(a^2-ab)-(ab-b^2)
=a.(a-b)-b(a-b)
=(a-b)(a-b)
=(a-b)^2(ĐPCM)
Vậy a^2+b^2-2ab=(a-b)^2