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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: Phân tích đa thức thành nhân tử a) ($2x+3y)^{2}$ b) ($5x-y)^{2}$ c) ($2x+y^{2}$)$^{3}$ d) ($x+1/4)^{2}$ e) ( $\frac{2}{3}$ $x^{

Toán Lớp 8: Phân tích đa thức thành nhân tử
a) ($2x+3y)^{2}$
b) ($5x-y)^{2}$
c) ($2x+y^{2}$)$^{3}$
d) ($x+1/4)^{2}$
e) ( $\frac{2}{3}$ $x^{2}$ – $\frac{1}{2}$ y) ^3

Comments ( 2 )

  1. a) (2x+3y)^2
    =(2x)^2 + 2.2x.3y + (3y)^2
    =4x^2 +12xy + 9y^2
    b) (5x-y)^2
    =(5x)^2 +2.5x.y +y^2
    =25x^2 +10xy +y^2
    c) (2x+y^2)^3
    =(2x)^3 +3.(2x)^2 .y^2+3.2x.(y^2)^2 +(y^2)^3
    =8x^3+3.4x^2 .y^2+3.2x.y^4 +y^6
    =8x^3 +12x^2y^2+6xy^4 +y^6
    d) (x+1/4)^2
    =x^2+2.1/4 .x +(1/4)^2
    =x^2+\frac{1}{2}x+1/16
    e) (\frac{2}{3}x^2-\frac{1}{2}y)^3
    =(\frac{2}{3}x^2)^3-3.(\frac{2}{3}x^2)^2 .\frac{1}{2}y+3.\frac{2}{3}x^2 .(\frac{1}{2}y)^2 – (\frac{1}{2}y)^3
    =\frac{8}{27}x^6-\frac{2}{3}x^4y+\frac{1}{2}x^2y-\frac{1}{8}y

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222-9+11+12:2*14+14 = ? ( )

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