题目内容
实践与探索:
(1)比较下列算式结果的大小:
42+32______2×4×3,(-2)2+12______ 2×(-2)×1,242+(
)2______2×24×
,22+22______2×2×2
(2)通过观察、归纳,比较:20072+20082______2×2007×2008;
(3)请你用字母a、b写出能反映上述规律的式子:______.
(1)比较下列算式结果的大小:
42+32______2×4×3,(-2)2+12______ 2×(-2)×1,242+(
1 |
24 |
1 |
24 |
(2)通过观察、归纳,比较:20072+20082______2×2007×2008;
(3)请你用字母a、b写出能反映上述规律的式子:______.
(1)42+32=16+9=25,2×4×3=24,;
(-2)2+12=4+1=5,2×(-2)×1=-4;
242+(
)2=576+
=576
,2×24×
=2;
22+22=4+4=8,2×2×2=8,.
则42+32>2×4×3,(-2)2+12>2×(-2)×1,242+(
)2>2×24×
,22+22=2×2×2;
(2)20072+20082>2×2007×2008;
(3)a2+b2≥2ab,当a=b≥0时,等号成立.
(-2)2+12=4+1=5,2×(-2)×1=-4;
242+(
1 |
24 |
1 |
576 |
1 |
576 |
1 |
24 |
22+22=4+4=8,2×2×2=8,.
则42+32>2×4×3,(-2)2+12>2×(-2)×1,242+(
1 |
24 |
1 |
24 |
(2)20072+20082>2×2007×2008;
(3)a2+b2≥2ab,当a=b≥0时,等号成立.
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