Question

八下数学分解因式的题（m+n）²-n² 49（a-b）²-16（a+b）² （2

Answer 1

（m+n）²-n²
=(m+n+n)(m+n-n)
=m(m+2n)
49（a-b）²-16（a+b）²
[7(a-b)+4(a+b)][7(a-b)-4(a+b)]
=(11a-3b)(3a-11b)
（2x+y）²-（x+2y）²
=[(2x+y)+(x+2y)][(2x+y)-(x+2y)]
=(3x+3y)(x-y)
=3(x+y)(x-y)
1/3m²-3n²
=1/3(m²-9n²)
=1/3(m+3n)(m-3n)
（a+b）²-（a-b）²
=[(a+b)+(a-b)][(a+b)-(a-b)]
=2a×2b
=4ab
（9a+4b）²-（3a-b）²
=[(9a+4b)+(3a-b)][9a+4b)-(3a-b)]
=(12a+3b)(6a+5b)
=3(4a+b)(6a+5b)