乘法公式的题目.1.已知a^2+b^2=12,且ab=-3,试求(a+b)^2的值.2.计算:(2x+y-z+10)X(2x-y+z+10)计算:(x-y+1)X(x+y-5)计算:(2a+1)^2(2a-1)^2 (这个我算的16a^4,但人家说答案是8a)以上都是用平方差公式和完全平方
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/30 04:29:46
![乘法公式的题目.1.已知a^2+b^2=12,且ab=-3,试求(a+b)^2的值.2.计算:(2x+y-z+10)X(2x-y+z+10)计算:(x-y+1)X(x+y-5)计算:(2a+1)^2(2a-1)^2 (这个我算的16a^4,但人家说答案是8a)以上都是用平方差公式和完全平方](/uploads/image/z/2600194-58-4.jpg?t=%E4%B9%98%E6%B3%95%E5%85%AC%E5%BC%8F%E7%9A%84%E9%A2%98%E7%9B%AE.1.%E5%B7%B2%E7%9F%A5a%5E2%2Bb%5E2%3D12%2C%E4%B8%94ab%3D-3%2C%E8%AF%95%E6%B1%82%28a%2Bb%29%5E2%E7%9A%84%E5%80%BC.2.%E8%AE%A1%E7%AE%97%EF%BC%9A%EF%BC%882x%2By-z%2B10%29X%282x-y%2Bz%2B10%29%E8%AE%A1%E7%AE%97%EF%BC%9A%28x-y%2B1%29X%28x%2By-5%29%E8%AE%A1%E7%AE%97%EF%BC%9A%282a%2B1%29%5E2%282a-1%29%5E2+%EF%BC%88%E8%BF%99%E4%B8%AA%E6%88%91%E7%AE%97%E7%9A%8416a%5E4%2C%E4%BD%86%E4%BA%BA%E5%AE%B6%E8%AF%B4%E7%AD%94%E6%A1%88%E6%98%AF8a%29%E4%BB%A5%E4%B8%8A%E9%83%BD%E6%98%AF%E7%94%A8%E5%B9%B3%E6%96%B9%E5%B7%AE%E5%85%AC%E5%BC%8F%E5%92%8C%E5%AE%8C%E5%85%A8%E5%B9%B3%E6%96%B9)
乘法公式的题目.1.已知a^2+b^2=12,且ab=-3,试求(a+b)^2的值.2.计算:(2x+y-z+10)X(2x-y+z+10)计算:(x-y+1)X(x+y-5)计算:(2a+1)^2(2a-1)^2 (这个我算的16a^4,但人家说答案是8a)以上都是用平方差公式和完全平方
乘法公式的题目.
1.已知a^2+b^2=12,且ab=-3,试求(a+b)^2的值.
2.计算:(2x+y-z+10)X(2x-y+z+10)
计算:(x-y+1)X(x+y-5)
计算:(2a+1)^2(2a-1)^2 (这个我算的16a^4,但人家说答案是8a)
以上都是用平方差公式和完全平方公式的.
乘法公式的题目.1.已知a^2+b^2=12,且ab=-3,试求(a+b)^2的值.2.计算:(2x+y-z+10)X(2x-y+z+10)计算:(x-y+1)X(x+y-5)计算:(2a+1)^2(2a-1)^2 (这个我算的16a^4,但人家说答案是8a)以上都是用平方差公式和完全平方
1
(a+b)^2=a^2+2ab+b^2=12+2*(-3)=6
2
(2x+y-z+10)(2x-y+z+10)
=[(2x+10)+(y-z)][(2x+10)-(y-z)]
=(2x+10)^2-(y-z)^2
=4x^2+40x+100-y^2+2yz-z^2
(x-y+1)(x+y-5)
=(x-y)(x+y)-5(x-y)+(x+y)-5
=x^2-y^2-4x+6y-5
(2a+1)^2(2a-1)^2
=[(2a+1)(2a-1)]^2
=(4a^2-1)^2
=16a^4-8a^2+1
(a+b)^2 = a^2 + 2ab + b^2=(a^2 + b^2)+2ab=12 + 2 X 3=18
(2x+y-z+10)X(2x-y+z+10)
=(2x+10+y-z)(2x+10-(y-z))
=(2x+10)^2-(y-z)^2 之后展开就成
(x-y+1)(x+y-5)
=x^2-y^2+(x+y)-5(x-y)-5
=(x^2-4X+4)-(y^2+6y+9)
=(x-2)^2-(y-3)^2
(2a+1)^2(2a-1)^2=[(2a+1)(2a-1)]^2
=(4a^2-1)^2
就这结果了