Question

Tính x,y 
a) 6x=9y và 2x + 3y= -72
     Giúp mình nha mik cần gấp ai làm nhanh thì mik k cho nha

Answer 1

3x2+2y2=7xy3x2+2y2=7xy

⇔3x2−7xy+2y2=0⇔3x2−7xy+2y2=0

⇔3x2−6xy−xy+2y2=0⇔3x2−6xy−xy+2y2=0

⇔3x(x−2y)−y(x−2y)=0⇔3x(x−2y)−y(x−2y)=0

⇔(3x−y)(x−2y)=0⇔(3x−y)(x−2y)=0

⇔[3x−y=0x−2y=0⇔[3x−y=0x−2y=0 ⇔[3x=yx=2y⇔[3x=yx=2y

+) TH1 : y=3xy=3x

⇔A=3x+y7y−x+6x−9y2x+y⇔A=3x+y7y−x+6x−9y2x+y

=3x+3x7.3x−x+6x−9.3x2x+3x=3x+3x7.3x−x+6x−9.3x2x+3x

=9x20x+−21x5x=9x20x+−21x5x

=−154=−154

+) TH2 : x=2yx=2y

⇔A=3x+y7y−x+6x−9y2x+y⇔A=3x+y7y−x+6x−9y2x+y

=3.2y+y7y−2y+6.2y−9y2.2y+y=3.2y+y7y−2y+6.2y−9y2.2y+y

=7y5y+3y5y=7y5y+3y5y

=2=2

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