Toán Lớp 8: a)x^2-6x+9-25y^2 b)5xy+z-5x-yz c)3x^2+6xy+3y^2-3x^2 d)x^2+3x-y^2+3y

Question

Toán Lớp 8:  a)x^2-6x+9-25y^2 b)5xy+z-5x-yz c)3x^2+6xy+3y^2-3x^2 d)x^2+3x-y^2+3y

maingocquynhnhu2k1 · Answer

a) x^2-6x+9-25y^2   =(x^2-6x+9)-25y^2   =(x-3)^2-(5y)^2   =(x-3-5y)(x-3+5y)   b) 5xy+z-5x-yz   =(5xy-5x)+(z-yz)   =5x(y-1)+z(1-y)   =5x(y-1)+z[-(y-1)]   =5x(y-1)-z(y-1)   =(5x-z)(y-1)   c) 3x^2+6xy+3y^2-3z^2   =3(x^2+2xy+y^2-z^2)   =3[(x^2+2xy+y^2)-z^2]   =3[(x+y)^2-z^2]   =3(x+y-z)(x+y+z)   d) x^2+3x-y^2+3y   =(x^2-y^2)+(3x+3y)   =(x-y)(x+y)+3(x+y)   =(x+y)(3+x-y)

ngochuong2k2 · Answer

Giải đáp+Lời giải và giải thích chi tiết:    a) x&sup2;-6x+9-25y&sup2;   =(x&sup2;-6x+9)-25y&sup2;   =(x-3)&sup2;-(5y)&sup2;   =(x-3-5y)(x-3+5y)   b) 5xy+z-5x-yz   =(5xy-5x)+(z-yz)   =(5xy-5x)-(yz-z)   =5x(y-1)-z(y-1)   =(y-1)(5x-z)   c) 3x&sup2;+6xy+3y&sup2;-3x&sup2;   =3(x&sup2;+2xy+y&sup2;-x&sup2;)   =3[(x&sup2;+2xy+y&sup2;)-x&sup2;]   =3[(x+y)&sup2;-x&sup2;]   =3(x+y-z)(x+y+z)   d) x&sup2;+3x-y&sup2;+3y   =(x&sup2;-y&sup2;)+(3x+3y)   =(x-y)(x+y)+3(x+y)   =(x+y)(x-y+3)           Ch&uacute;c bn hc tốt   ????               $ text{#Hưng}$