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(2x+3y)^3=?
ajutati ma!!


Răspuns :

(2x+3y)³=

(2x+3y)(2x)²+2•2x•3y+(3y)²)=

(2x+3y)(2²x²+2•2x•3y+(3y)²)=

(2x+3y)(4x²+2•2x•3y+3²y²)=

(2x+3y)(4x²+2•2x•3y+9y²)=

(2x+3y)(4x²+12xy+9y²)=

2x(4x²+12xy+9y²)+3y(4x²+12xy+9y²)=

8x³+24x²y+18xy²+3y(4x²+12xy+9y²)=

8x³+24x²y+18xy²+12yx²+36y²x+27y³=

8x³+(24x²y+12x²y)+(18xy²+36xy²)+27y³=

8x³+36x²y+54xy²+27y³