1.(a-3)^2=(a+3)^2+( )成立,则括号中应填A.12a B.-12a C.6a D.-6a2.如果(x+4)(x-5)=x^2+px+q,那么p,q的值是( )A.P=1 Q=20 B.P=1 Q=-20 C.P=-1 Q=-20 D.P=-1 Q=203.下列计算中能用平方差公式计算的是A.(3a+b)(a-3b) B.(3a+b)(3
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![1.(a-3)^2=(a+3)^2+( )成立,则括号中应填A.12a B.-12a C.6a D.-6a2.如果(x+4)(x-5)=x^2+px+q,那么p,q的值是( )A.P=1 Q=20 B.P=1 Q=-20 C.P=-1 Q=-20 D.P=-1 Q=203.下列计算中能用平方差公式计算的是A.(3a+b)(a-3b) B.(3a+b)(3](/uploads/image/z/1780969-49-9.jpg?t=1.%EF%BC%88a-3%29%5E2%3D%28a%2B3%29%5E2%2B%28+%29%E6%88%90%E7%AB%8B%2C%E5%88%99%E6%8B%AC%E5%8F%B7%E4%B8%AD%E5%BA%94%E5%A1%ABA.12a+B.-12a+C.6a+D.-6a2.%E5%A6%82%E6%9E%9C%EF%BC%88x%2B4%EF%BC%89%28x-5%29%3Dx%5E2%2Bpx%2Bq%2C%E9%82%A3%E4%B9%88p%2Cq%E7%9A%84%E5%80%BC%E6%98%AF%EF%BC%88+%EF%BC%89A.P%3D1+Q%3D20+B.P%3D1+Q%3D-20+C.P%3D-1+Q%3D-20+D.P%3D-1+Q%3D203.%E4%B8%8B%E5%88%97%E8%AE%A1%E7%AE%97%E4%B8%AD%E8%83%BD%E7%94%A8%E5%B9%B3%E6%96%B9%E5%B7%AE%E5%85%AC%E5%BC%8F%E8%AE%A1%E7%AE%97%E7%9A%84%E6%98%AFA.%283a%2Bb%29%28a-3b%29+B.%283a%2Bb%29%283)
1.(a-3)^2=(a+3)^2+( )成立,则括号中应填A.12a B.-12a C.6a D.-6a2.如果(x+4)(x-5)=x^2+px+q,那么p,q的值是( )A.P=1 Q=20 B.P=1 Q=-20 C.P=-1 Q=-20 D.P=-1 Q=203.下列计算中能用平方差公式计算的是A.(3a+b)(a-3b) B.(3a+b)(3
1.(a-3)^2=(a+3)^2+( )成立,则括号中应填
A.12a B.-12a C.6a D.-6a
2.如果(x+4)(x-5)=x^2+px+q,那么p,q的值是( )
A.P=1 Q=20 B.P=1 Q=-20 C.P=-1 Q=-20 D.P=-1 Q=20
3.下列计算中能用平方差公式计算的是
A.(3a+b)(a-3b) B.(3a+b)(3a-b) C.(3a+b)(-3a-b) D.(-3a+b)(3a-b)
4.先化简,再求值
(1)已知x(x-1)-(x^2-y)=-3,求(y-x+2xy)/2-xy
(2)当x=2,y=1/2时,求代数式(x+y)(x-y)+(x-y)^2-(x^2-3XY)的值
1.(a-3)^2=(a+3)^2+( )成立,则括号中应填A.12a B.-12a C.6a D.-6a2.如果(x+4)(x-5)=x^2+px+q,那么p,q的值是( )A.P=1 Q=20 B.P=1 Q=-20 C.P=-1 Q=-20 D.P=-1 Q=203.下列计算中能用平方差公式计算的是A.(3a+b)(a-3b) B.(3a+b)(3
1.B.-12a
2. C.P=-1 Q=-20
3.B.(3a+b)(3a-b)
4.
(1)x(x-1)-(x^2-y)=x^2-x-x^2+y=-3
y-x=-3
(y-x+2xy)/2-xy=(y-x)/2+xy-xy=-3/2
(2)(x+y)(x-y)+(x-y)^2-(x^2-3xy)
=x^2-y^2+x^2-2xy+y^2-x^2+3xy
=x^2+xy
=4+1
=5
1.B 2.C 3.B
4(1) X^2-X-X^2+Y=-3
-X+Y=-3
X-Y=3
(y-x+2xy)/2-xy
=(Y-X)/2
=-1.5
(2)(x+y)(x-y)+(x-y)^2-(x^2-3XY)
=X^2-Y^2+X^2-2XY+Y^2-X^2+3XY
=X(X+Y)=2(2+1/2)=5