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(12x+5y)²=
(2x-9y)²=​


Răspuns :

Salut!

(12x+5y)²

=(12x)²+2·12x·5y+(5y)²

=144x²+120xy+25y²

(2x-9y)²

=(2x)²-2·2x·9y+(9y)²

=4x²-36xy+81y²

Succes!

(12x+5y)²=

=(12x)²+2×12x×5y+(5y)²=144x²+120xy+25y²

(2x-9y)²=

=(2x)²-2×2x×9y+(9y)²=4x²-36xy+81y²