標題:
10分~有三條英文數學題唔識,邊個可以教我(要列式同過程)???
發問:
要用代數式(equation)1.the total age of mr.chu and his son is 51.three years ago,he was 8times as old as his son.how old is his son now?2.the difference between the present ages of mr.chan and his son is 32.6 years later,their total age will be 50 . how old is his son now?3:72 marbles are divided into two portions so... 顯示更多 要用代數式(equation) 1.the total age of mr.chu and his son is 51.three years ago,he was 8times as old as his son.how old is his son now? 2.the difference between the present ages of mr.chan and his son is 32.6 years later,their total age will be 50 . how old is his son now? 3:72 marbles are divided into two portions so that 7 times the smaller portion equals 5 times the bigger portion. find the number of marbles in the smaller portion. 要10分就快d喇...
最佳解答:
1) the answer is 8 years old. Let the son is X years old now and his father is Y years old now. X + Y = 51 equation 1 Y - 3 = 8(X - 3) equation 2 Y - 3 = 8X -24 Y = 8X - 21 equation 3 X + (8X -21) = 51 put equation 3 into 1 9X - 21 = 51 9X = 72 X = 8 2) The answer is 3 years old. Let Mr.Chan is Y years-old now, and his son is X years-old now. Y - X = 32 equation 1 (Y + 6) + (X + 6) = 50 equation 2 X + Y + 12 = 50 X + Y = 38 Y = 38 - X equation 3 38 - X - X = 32 put equation 3 into 1 38 - 2X = 32 2X = 6 X = 3 3) the answer is 30 marbles Let the small bag of marbles is X, and the big bag of marbles is Y. 7X = 5Y equation 1 X + Y = 72 equation 2 X = 72 - Y from equation 2 7(72 - Y) = 5Y put equation 2 into 1 504 = 12Y Y = 42 X = 30
其他解答:
1及3 都對 2. x-y=32 -------(1) x+6+y+6=50 --------(2) (2)-(1) 2y+12=50 -32 2y = 6 y = 3|||||1. Let Mr. Chu be x years old and his son be y years old x + y = 51 - (1) x - 3 = 8 (y-3) - (2) By eliminating x in the 2 equations, (1) - (2): y + 3 = 51 - 8y + 24 so, y = 8 The son is 8 years old. 2. Let Mr. Chan is x years old now, his son is y years old now x + y = 50 x - y = 32.6 By eliminating x in the 2 equations, (1) - (2): 2y = 50 - 32.6 so, y = 8.7 The son is 8.7 years old. 3 Let the no. of larger portion be x; the smaller portion be y x + y = 72 , so y= 72 - x 5x = 7y Sub y = 72 - x into 5x = 7y 5(72-y) = 7y y = 30 No. of marbles in smaller portion = 30|||||1. Let x be the age of Mr. Chu's son y be the age of Mr. Chu x + y = 51 y-3= 8(x-3) x + y = 51 y = 51-x y-3 = 8(x-3) 51-x-3 = 8x-24 9x = 72 x=8 if x = 8 8+y = 51 y = 43 So his son is 8 years old now. 2. Let x be the age of Mr. Chan's son y be the age of Mr. Chan y-x = 32.6 x+y = 50 x+y = 50 x = 50-y y-x = 32.6 y-(50-y) = 32.6 y-50+y = 32.6 2y - 50 = 32.6 2y = 82.6 y = 41.3 if y = 41.3 x+y = 50 x+41.3 = 50 x = 8.7 So his son is 8.7 years old now. 3. Let x be the number of marbles of smaller portion y be the number of marbles of bigger portion x+y = 72 7x = 5y x+y = 72 y = 72-x 7x = 5y 7x = 5(72-x) 7x = 360-5x 12x = 360 x = 30 if x = 30 30+y = 72 y = 42 So the number of marbles in the smaller portion is 30.
10分~有三條英文數學題唔識,邊個可以教我(要列式同過程)???
發問:
要用代數式(equation)1.the total age of mr.chu and his son is 51.three years ago,he was 8times as old as his son.how old is his son now?2.the difference between the present ages of mr.chan and his son is 32.6 years later,their total age will be 50 . how old is his son now?3:72 marbles are divided into two portions so... 顯示更多 要用代數式(equation) 1.the total age of mr.chu and his son is 51.three years ago,he was 8times as old as his son.how old is his son now? 2.the difference between the present ages of mr.chan and his son is 32.6 years later,their total age will be 50 . how old is his son now? 3:72 marbles are divided into two portions so that 7 times the smaller portion equals 5 times the bigger portion. find the number of marbles in the smaller portion. 要10分就快d喇...
最佳解答:
1) the answer is 8 years old. Let the son is X years old now and his father is Y years old now. X + Y = 51 equation 1 Y - 3 = 8(X - 3) equation 2 Y - 3 = 8X -24 Y = 8X - 21 equation 3 X + (8X -21) = 51 put equation 3 into 1 9X - 21 = 51 9X = 72 X = 8 2) The answer is 3 years old. Let Mr.Chan is Y years-old now, and his son is X years-old now. Y - X = 32 equation 1 (Y + 6) + (X + 6) = 50 equation 2 X + Y + 12 = 50 X + Y = 38 Y = 38 - X equation 3 38 - X - X = 32 put equation 3 into 1 38 - 2X = 32 2X = 6 X = 3 3) the answer is 30 marbles Let the small bag of marbles is X, and the big bag of marbles is Y. 7X = 5Y equation 1 X + Y = 72 equation 2 X = 72 - Y from equation 2 7(72 - Y) = 5Y put equation 2 into 1 504 = 12Y Y = 42 X = 30
其他解答:
1及3 都對 2. x-y=32 -------(1) x+6+y+6=50 --------(2) (2)-(1) 2y+12=50 -32 2y = 6 y = 3|||||1. Let Mr. Chu be x years old and his son be y years old x + y = 51 - (1) x - 3 = 8 (y-3) - (2) By eliminating x in the 2 equations, (1) - (2): y + 3 = 51 - 8y + 24 so, y = 8 The son is 8 years old. 2. Let Mr. Chan is x years old now, his son is y years old now x + y = 50 x - y = 32.6 By eliminating x in the 2 equations, (1) - (2): 2y = 50 - 32.6 so, y = 8.7 The son is 8.7 years old. 3 Let the no. of larger portion be x; the smaller portion be y x + y = 72 , so y= 72 - x 5x = 7y Sub y = 72 - x into 5x = 7y 5(72-y) = 7y y = 30 No. of marbles in smaller portion = 30|||||1. Let x be the age of Mr. Chu's son y be the age of Mr. Chu x + y = 51 y-3= 8(x-3) x + y = 51 y = 51-x y-3 = 8(x-3) 51-x-3 = 8x-24 9x = 72 x=8 if x = 8 8+y = 51 y = 43 So his son is 8 years old now. 2. Let x be the age of Mr. Chan's son y be the age of Mr. Chan y-x = 32.6 x+y = 50 x+y = 50 x = 50-y y-x = 32.6 y-(50-y) = 32.6 y-50+y = 32.6 2y - 50 = 32.6 2y = 82.6 y = 41.3 if y = 41.3 x+y = 50 x+41.3 = 50 x = 8.7 So his son is 8.7 years old now. 3. Let x be the number of marbles of smaller portion y be the number of marbles of bigger portion x+y = 72 7x = 5y x+y = 72 y = 72-x 7x = 5y 7x = 5(72-x) 7x = 360-5x 12x = 360 x = 30 if x = 30 30+y = 72 y = 42 So the number of marbles in the smaller portion is 30.
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