Các câu hỏi tương tự
cmr:
A)\(a^3+b^3=\left(a+b\right)\left[\left(a-b\right)^2+ab\right]\)
B)\(\left(a^2+b^2\right)\left(c^2+d^2\right)=\left(ac+bd\right)^2+\left(ad-bc\right)^2\)
Chứng minh rằng :
b) \(a^3+b^3=\left(a+b\right)\left[\left(a-b\right)^2+ab\right]\)
c) \(\left(a^2+b^2\right)\left(c^2+d^2\right)=\left(ac+bd\right)^2+\left(ad-bc\right)^2\)
left(a+b+cright)^3-a^3-b^3-c^3left[left(a+bright)+cright]^3-a^3-b^3-c^3left(a+bright)^3+3left(a+bright)^2c+3left(a+bright)c^2+c^3-a^3-b^3-c^3a^3+3a^2b+3ab^2+b^3+3cleft(a^2+2ab+b^2right)+3ac^2+3bc^2-a^3-b^33a^2b+3ab^2+3a^2c+6abc+3b^2c+3ac^2+3bc^23left(a^2b+ab^2+a^2c+ac^2+b^2c+bc^2+2abcright)3left[left(a^2b+ab^2right)+left(a^2c+abcright)+left(ac^2+bc^2right)+left(b^2c+abcright)right]3left[ableft(a+bright)+acleft(a+bright)+c^2left(a+bright)+bcleft(a+bright)right]3left(a+bright)left(ab+ac+c^2+bcrigh...
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\(\left(a+b+c\right)^3-a^3-b^3-c^3\)
\(=\left[\left(a+b\right)+c\right]^3-a^3-b^3-c^3\)
\(=\left(a+b\right)^3+3\left(a+b\right)^2c+3\left(a+b\right)c^2+c^3-a^3-b^3-c^3\)
\(=a^3+3a^2b+3ab^2+b^3+3c\left(a^2+2ab+b^2\right)+3ac^2+3bc^2-a^3-b^3\)
\(=3a^2b+3ab^2+3a^2c+6abc+3b^2c+3ac^2+3bc^2\)
\(=3\left(a^2b+ab^2+a^2c+ac^2+b^2c+bc^2+2abc\right)\)
\(=3\left[\left(a^2b+ab^2\right)+\left(a^2c+abc\right)+\left(ac^2+bc^2\right)+\left(b^2c+abc\right)\right]\)
\(=3\left[ab\left(a+b\right)+ac\left(a+b\right)+c^2\left(a+b\right)+bc\left(a+b\right)\right]\)
\(=3\left(a+b\right)\left(ab+ac+c^2+bc\right)\)
\(=3\left(a+b\right)\left[a\left(b+c\right)+c\left(b+c\right)\right]\)
\(=3\left(a+b\right)\left(b+c\right)\left(c+b\right)\)
65. Phân tích đa thức thành nhân tửa) ableft(a+bright)-bcleft(b+cright)+acleft(a-cright)b) aleft(b^2+c^2right)+bleft(c^2+a^2right)+cleft(a^2+b^2right)+2abcc) left(a+bright)left(a^2-b^2right)+left(b+cright)left(b^2+c^2right)+left(c+aright)left(c^2+a^2right)d) a^3left(b-cright)+b^3left(c-aright)+c^3left(a-bright)e) a^3left(c-b^2right)+b^3left(a-c^2right)+c^3left(b-a^2right)+abcleft(abc-1right)
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65. Phân tích đa thức thành nhân tử
a) \(ab\left(a+b\right)-bc\left(b+c\right)+ac\left(a-c\right)\)
b) \(a\left(b^2+c^2\right)+b\left(c^2+a^2\right)+c\left(a^2+b^2\right)+2abc\)
c) \(\left(a+b\right)\left(a^2-b^2\right)+\left(b+c\right)\left(b^2+c^2\right)+\left(c+a\right)\left(c^2+a^2\right)\)
d) \(a^3\left(b-c\right)+b^3\left(c-a\right)+c^3\left(a-b\right)\)
e) \(a^3\left(c-b^2\right)+b^3\left(a-c^2\right)+c^3\left(b-a^2\right)+abc\left(abc-1\right)\)
65. Phân tích đa thức thành nhân tửa) ableft(a+bright)-bcleft(b+cright)+acleft(a-cright)b) aleft(b^2+c^2right)+bleft(c^2+a^2right)+cleft(a^2+b^2right)+2abcc) left(a+bright)left(a^2-b^2right)+left(b+cright)left(b^2-c^2right)+left(c+aright)left(c^2-a^2right)d) a^3left(b-cright)+b^3left(c-aright)+c^3left(a-bright)e) a^3left(c-b^2right)+b^3left(a-c^2right)+c^3left(b-a^2right)+abcleft(abc-1right)
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65. Phân tích đa thức thành nhân tử
a) \(ab\left(a+b\right)-bc\left(b+c\right)+ac\left(a-c\right)\)
b) \(a\left(b^2+c^2\right)+b\left(c^2+a^2\right)+c\left(a^2+b^2\right)+2abc\)
c) \(\left(a+b\right)\left(a^2-b^2\right)+\left(b+c\right)\left(b^2-c^2\right)+\left(c+a\right)\left(c^2-a^2\right)\)
d) \(a^3\left(b-c\right)+b^3\left(c-a\right)+c^3\left(a-b\right)\)
e) \(a^3\left(c-b^2\right)+b^3\left(a-c^2\right)+c^3\left(b-a^2\right)+abc\left(abc-1\right)\)
Chứng minh đẳng thức :
a) \(\left(a^2+b^2\right)\left(c^2+d^2\right)=\left(ac+bd\right)^2+\left(ad-bc\right)^2\))^2
b) \(\left(a+b+c\right)+a^2+b^2+c^2=\left(a+b\right)^2+\left(b+c\right)^2+\left(c+a\right)^2\)
( Mình đang cần gấp . Đảm bảo tick trả đầy đủ =))
1 tháng 6 2019 lúc 9:50
\(CMR:a^3+b^3+c^3-3abc=\left(a+b+c\right)\left(a^2+b^2+c^2-ab-bc-ac\right)\)
Cho a,b,c,d là các số thực. Chứng minh rằng:
\(\left(ac+bd\right)^2+\left(ad-bc\right)^2=\left(a^2+b^2\right)\left(c^2+d^2\right)\)
Chứng minh rằng:
a) \(\left(a^2-b^2\right)\left(c^2-d^2\right)=\left(ac+bd\right)^2-\left(ad+bc\right)^2\)
b) Nếu \(x^2+y^2+z^2=xy+xz+yz\) thì x=y=z