解方程:(2a-3)^3=(2a+1)(2a-1)-21.已知:(a+b)^2=7,(a-b)^2=4,求a^2+b^2和ab的值2.(a+b)(a-b)+(a+b)^2-2a(a+b)3.分解因式:(1) (a-b)(a^2+2a+4) (2) (2x-y)(4x^2+2xy+4y^2)直接用公式:(1) (3x-2y)(9x^2+6xy+4y^2)(2) (2m-3)(

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解方程:(2a-3)^3=(2a+1)(2a-1)-21.已知:(a+b)^2=7,(a-b)^2=4,求a^2+b^2和ab的值2.(a+b)(a-b)+(a+b)^2-2a(a+b)3.分解因式:(1) (a-b)(a^2+2a+4) (2) (2x-y)(4x^2+2xy+4y^2)直接用公式:(1) (3x-2y)(9x^2+6xy+4y^2)(2) (2m-3)(
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解方程:(2a-3)^3=(2a+1)(2a-1)-21.已知:(a+b)^2=7,(a-b)^2=4,求a^2+b^2和ab的值2.(a+b)(a-b)+(a+b)^2-2a(a+b)3.分解因式:(1) (a-b)(a^2+2a+4) (2) (2x-y)(4x^2+2xy+4y^2)直接用公式:(1) (3x-2y)(9x^2+6xy+4y^2)(2) (2m-3)(
解方程:(2a-3)^3=(2a+1)(2a-1)-2
1.已知:(a+b)^2=7,(a-b)^2=4,求a^2+b^2和ab的值
2.(a+b)(a-b)+(a+b)^2-2a(a+b)
3.分解因式:(1) (a-b)(a^2+2a+4) (2) (2x-y)(4x^2+2xy+4y^2)
直接用公式:
(1) (3x-2y)(9x^2+6xy+4y^2)
(2) (2m-3)(4m^2+ _____________ +9)= _____________
乘法公式:
(1) a(a+b)-b(a-b) (2) (2x+5)(x-5)
(3) (3x+1)^2(3x-1)^2 (4) (2x-3y)^2-(y+3x)(3x-y)
(5) (2m+1-3n)(2m-1+3n) (6)503*497

解方程:(2a-3)^3=(2a+1)(2a-1)-21.已知:(a+b)^2=7,(a-b)^2=4,求a^2+b^2和ab的值2.(a+b)(a-b)+(a+b)^2-2a(a+b)3.分解因式:(1) (a-b)(a^2+2a+4) (2) (2x-y)(4x^2+2xy+4y^2)直接用公式:(1) (3x-2y)(9x^2+6xy+4y^2)(2) (2m-3)(
1.已知:(a+b)^2=7,(a-b)^2=4,求a^2+b^2和ab的值
(a+b)²=7===>a²+2ab+b²=7(1)
(a-b)²=4====>a²-2ab+b²=4(2)
(1)+(2)a²+b²=11/2
(1)-(2)4ab=3===>ab=3/4
2.(a+b)(a-b)+(a+b)^2-2a(a+b)
=a²-b²+a²+2ab+b²-2a²-2ab=2ab-2ab=0或=(a+b)(a-b-2a)+(a+b)²=(a+b)²-(a+b)²=0
3.分解因式:(1) (a-b)(a^2+2a+4)
(2) (2x-y)(4x^2+2xy+4y^2)=2(2x-y))(2x^2+xy+2y^2)
直接用公式:
(1) (3x-2y)(9x^2+6xy+4y^2)=27x^3-8y^3
(2) (2m-3)(4m^2+ ______6m_______ +9)= ___8m^3-27__________
乘法公式:
(1) a(a+b)-b(a-b)=a²+ab-ab+b²=a²+b² (2) (2x+5)(x-5)=2x²-10x+5x-25=2x²-5x-25
(3) (3x+1)^2(3x-1)^2=[(3x+1)(3x-1)]²=(9x²-1)²=81x^4-18x²+1
(4) (2x-3y)^2-(y+3x)(3x-y)=4x²-12xy+9y²-9x²+y²=-5x²-12xy+10y²
(5) (2m+1-3n)(2m-1+3n)=(2m+1-3n)[2m-(1-3n)]=4m²-(1-3n)²=4m²-9n²+6n-1
(6)503*497=(500+3)(500-3)=500²-9=250000-9=249991