標題:
F.3 一元二次
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發問:
show the step plz! 1) It is given that x is greater than y by 6, and the sum of 2 times x and 3 times y is 22.find the values of x and y. ans : x=8,y=2 2) The sum of two numbers is 41.lf the larger number is 5 greater than twice the smaller number.find the two number ams: 12,29
最佳解答:
1) x = y + 6 ...(1) 2x + 3y = 22 ...(2) Sub (1) into (2), 2(y + 6) + 3y = 22 2y + 12 + 3y = 22 5y = 22 - 12 y = 2 Sub into (1), y = 2 + 6 = 8 2) Let the larger number be x and the smaller one y x + y = 41 ... (1) x = 5 + 2y ... (2) Sub (2) into (1), (5 + 2y) + y = 41 3y = 41 - 5 y = 12 Sub into (2), x = 5 + 2(12) = 29
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