✔ 最佳答案
{1}
若 a - b = 5, ab = 1
(1)
a × a + b × b
= a² + b²
= a² - 2ab + b² + 2ab
= (a - b)² + 2ab
= 5² + 2(1)
= 25 + 2
= 27
(2)
(a + b) × (a + b)
= (a + b)²
= a² + 2ab + b²
= a² - 2ab + b² + 4ab
= (a - b)² + 4ab
= 5² + 4(1)
= 25 + 4
= 29
❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀
{2}
(249/10) × (251/10) = a + b, 若 a 為正整數且 0 < b < 1, 則 a = ?
a + b
= (249/10) × (251/10)
= (250 - 1)/10 × (250 + 1)/10
= (250² - 1²)/10²
= (62500 - 1)/100
= 625 - 0.01
= 624.99
b = 0.99
a = 624
❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀
{3}
大圓半徑為96, 小圓半徑為4,
大圓減小圓面積
= π(96)² - π(4)²
= π(96² - 4²)
= π(96 + 4)(96 - 4)
= π(100)(92)
= 9200π
❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀
{4}
997 × 997 + 1994 = ( ) × ( ) - 1, 求括號中的數
997 × 997 + 1994
= 997² + 2 × 997
= 1 + 2 × 997 + 997² - 1
= (1 + 997)² - 1
= 998² - 1
= 998 × 998 - 1
❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀
{5}
2345 × 3345 × (3345/2345 - 2345/3345)
= a × b × (b/a - a/b) 記 a = 2345 及 b = 3345
= a × b × b/a - a × b × a/b
= b² - a²
= 3345² - 2345²
= (3345 + 2345)(3345 - 2345)
= 5690 × 1000
= 5690000
❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀
{6}
邊長是100的正方形內, 每一橫線, 直線間隔都是1, 且白藍相間, 試問藍色部分的面積總共是多少平方單位?
類似下圖(藍白各佔一半):
□■□■□■□■□■
■□■□■□■□■□
□■□■□■□■□■
■□■□■□■□■□
□■□■□■□■□■
■□■□■□■□■□
□■□■□■□■□■
■□■□■□■□■□
□■□■□■□■□■
■□■□■□■□■□
藍色部分的面積
= 總面積 ÷ 2
= 100² ÷ 2
= 10000 ÷ 2
= 5000
❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀
{7}
1.98 × 1.98 - 4 × 1.98 + 4 + 2.02 × 1.98
= 1.98² - 2(1.98)(2) + 2² + (2 + 0.02) × (2 - 0.02)
= (1.98 - 2)² + 2² - 0.02²
= 0.02² + 2² - 0.02²
= 2²
= 4
❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀ ✿ ❀
{8}
63 × 61 + 64 × 64 - 64 × 62 - 62 × 62
= 63 × 61 - 62 × 62 + 64 × 64 - 64 × 62
= (62 + 1)(62 - 1) - 62² + 64(64 - 62)
= 62² - 1² - 62² + 64(2)
= -1² + 64(2)
= -1 + 128
= 127
2015-07-03 12:36:23 補充:
佳琪 同學~
加油~! 希望透過不同的途徑去學習~
最緊要學懂之後不單可以應付考試,而且可以再進一步學高深的數學~
╭∧---∧╮
│ .✪‿✪ │
╰/) ⋈ (\\╯