Toán Lớp 9: Rút gọn các biểu thức sau:
a, (2x+3)^2 – (2x-3)^2
b, (x-2y)^3 + (x+2y)^3
c, (2x+3). (3-2x)+4x^2
d, (x-3y).(x^2 + 3xy+9y2)- (x+3+y). (x^2 – 3xy +9y^2)
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Toán Lớp 9: Rút gọn các biểu thức sau:
a, (2x+3)^2 – (2x-3)^2
b, (x-2y)^3 + (x+2y)^3
c, (2x+3). (3-2x)+4x^2
d, (x-3y).(x^2 + 3xy+9y2)- (x+3+y). (x^2 – 3xy +9y^2)
Comments ( 2 )
=4x^2+12x+9-(4x^2-12x+9)
=4x^2+12x+9-4x^2+12x-9
=24x
=x^3-6x^2y+12xy^2-8y^3+x^3+6x^2y+12xy^2+8y^3
=2x^3+24xy^2
=9-4x^2+4x^2
=9
=x^3-27y^3- (x^3+27y^3)
=x^3-27y^3- x^3-27y^3
=-54y^3