2 、( x-3y+4z)？ =(x-3y)^2+2(x-3y)(4z)+(4z)^2=x^2-6xy+9y^2+8xz-24yz+ 16z^2

3 、( a+2b)(a-3b)-(-a-3b)？ =(a+2b)(a-3b)-[-(a+3b)]^2=a^2-ab-6b^2-(a^2+6ab+9b^2)=-7ab- 15b^2

4 、( 3x+2y)？ +(2y-3x)？ =9x^2+ 12xy+4y^2+4y^2- 12xy+9x^2= 18x^2+8y^2

5. Known: 3 5 * 27? = 9 m+ 1。 After simplification, find the value of the algebraic expression 2m (m-1)-(m+2) (m-4): 2m (m-1)-(m+2) (m-4) = 2m 2. =9^m+ 1,3^5*3^9=3^(m+ 1),3^ 14=3^(m+ 1),m= 13,m^2+8

6. Simplification: (-2xy? )(3xy-4xy？ + 1)

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