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發問:
1) Find two numbers such that four times the first and three times the second together make 65, while twice the first together with six times the second make 82.2) The difference between two number is 5. If the lager number is added to twice the smaller number, the sum is 59.Find the numbers.3)The difference of... 顯示更多 1) Find two numbers such that four times the first and three times the second together make 65, while twice the first together with six times the second make 82. 2) The difference between two number is 5. If the lager number is added to twice the smaller number, the sum is 59.Find the numbers. 3)The difference of two number is four-fifths of thei sum, and the bigger number exceeds six times the smaller number by 21.Find the numbers. 可不可以詳細少少話我知怎樣計~ Thank You
最佳解答:
1.let x be the first no.and y be another no. 4x+3y=65----(1) 2x+6y=82----(2) (1)x2, 8x+6y=130----(3) (3)-(2), 6x=48 x=8 sub x=8 into (1) 4(8)+3y=65 3y=65-32 y= 11 therefore, the first no. is 8, and another no. is 11. 2.let x be the larger no. and y be the smaller no. x-y=5-----(1) x+2y=59-----(2) (2)-(1), 3y=54 y=18 sub y=18 into(1) x-18=5 x=23 there, the larger no. is 23, and the smaller no. is 18. 3.let x be the bigger no. and y be the smaller no. x-y=x+y(4/5)-----(1) x=6y+21-----(2) from(1) x-y=4x+4y/5 5x-5y=4x+4y x=9y-----(3) sub(3) into(2) 9y=6y+21 3y=21 y=7 sub y=7 into (3) x=9(7) x=63 therefore, the bigger no. is 63, and the smaller no. is 7.
其他解答:
1) Find two numbers such that four times the first number and three times the second together make 65, while twice the first together with six times the second make 82 Let the fist number be a, second number be b 4a + 3b = 65.............(1) 2a + 6b = 82.............(2) (2) x 2 : 4a + 12b = 164..........(3) (3) - (1) 4a + 12b - 4a - 3b = 164 - 65 9b = 99 b = 11 // Substitute b = 11 into (2) 2a + 66 = 82 2a = 16 a = 8 // The first number is 8, second number is 11 2) The difference between two number is 5. If the lager number is added to twice the smaller number, the sum is 59.Find the numbers Let the larger number be a, smaller number be b a - 5 = b.............(1) a + 2b = 59.........(2) Substitute (1) into (2): a + 2( a-5 ) = 59 a + 2a - 10 = 59 3a = 69 a = 23 // Substitute a = 23 into (1) b = 23 - 5 b = 18 // The larger number is 23, smaller number is 18 3)The difference of two number is four-fifths of their sum, and the bigger number exceeds six times the smaller number by 21.Find the numbers Let the bigger number be a, smaller number be b ( a + b ) x ( 4/5) = a - b .........(1) a - 21 = 6b ...........................(2) From (2), a = 6b + 21............................(3) Substitute (3) into (1) ( 6b + 21 + b ) x (4/5) = 6b + 21 - b ( 7b + 21 ) x ( 4/5 ) = 5b + 21 4( 7b + 21 ) = 5( 5b + 21 ) 28b + 84 = 25b + 105 3b = 21 b = 7 // Substitute b = 7 into (3) a = 6(7) + 21 a = 42 + 21 a = 63 // The bigger number is 63, smaller number is 7 2007-02-12 18:26:17 補充： 難以相信佢會得到最佳回答囉~ 我每一條式都列得清清楚楚, 盡量對齊 D 位, 每一個 term 都留有少少 space, 等發問者容易 D 明白, 容易 D 理解, 而且我肯定我的 step 係比呢個答案詳細, 再加上我早佢成一日答呢條問題~ 如果咁講, 我 D steps 打得仲耐啦~ ( 十分心淡 ) 若大家同意, 請評下理~
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