1) Make the letter in the square brackets the subject of the formula.
l=a+(n-1)d [n]
2)The full fare for a tunnel bus is $12. It is known that m members of Mr Ho's family travelled on that bus and n of them paid half fare.
a)Express the total fare $T they paid in terms of m and n, and simplify the formula obtained.
b)Change the subject of the formula obtained in part(a) to n.
c)If 11 family members took that bus and the total fare was $108, how many of them paid half fare?
(Please show the processes of solving problems. )
Maths problems
2008-11-09 1:13 am
回答 (2)
2008-11-09 1:22 am
✔ 最佳答案
1)l = a + (n - 1)d
(n - 1)d = l - a
nd - d = l - a
nd = l - a + d
n = (l - a + d)/d
2a)
T = 12(m - n) + 6n = 12m - 6n
2b)
From (2a),
T = 12m - 6n
6n = 12m - T
n = (12m - T)/6
2c)
Sub m = 11, T = 108 into (2b)
n = (12 x 11 - 108)/6 = 24/6 = 4
2008-11-09 1:38 am
1. I= a+(n-1)d
I-a = (n-1)d
n-1 = (I-a) / d
n = (I-a) / d + 1
n = (I-a+d) / d
2a) T = 6n + 12(m-n)
T = 6n+12m-12n
T = 12m-6n
2b) T = 12m-6n
6n = 12m-T
n = (12m-T) / 6
2c) Sub m=11 and T=108 into 2b)
n = (12m-T) / 6
n = [(12)(11)-108] / 6
n = (132-108) / 6
n = 24 / 6
n = 4
I-a = (n-1)d
n-1 = (I-a) / d
n = (I-a) / d + 1
n = (I-a+d) / d
2a) T = 6n + 12(m-n)
T = 6n+12m-12n
T = 12m-6n
2b) T = 12m-6n
6n = 12m-T
n = (12m-T) / 6
2c) Sub m=11 and T=108 into 2b)
n = (12m-T) / 6
n = [(12)(11)-108] / 6
n = (132-108) / 6
n = 24 / 6
n = 4
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