Option A: x=12 3/7
Option B: x = 15
Option C: x=39 3/4
Option D: x = 94
Solve. 4/7=21/x-3 Help?
2008-12-17 2:43 pm
回答 (9)
2008-12-17 3:37 pm
✔ 最佳答案
4/7=12/x-3[4/7=21/x-3]7(x-3) lcd is 7(x-3)
4(x-3)=21(7)
4x-12=147
4x=147+12
4x=159
x=159/4 or 39 3/4 Answer C. x=39 3/4
2008-12-17 2:49 pm
4/7 = 21/(x - 3)
[7][x - 3][4/7] = [7][x - 3][21/(x - 3)]
4(x - 3) = 7(21)
4*x - 4*3 = 147
4x - 12 = 147
4x = 147 + 12
x = 159/4
x = 39 3/4 (39.75)
(option C)
[7][x - 3][4/7] = [7][x - 3][21/(x - 3)]
4(x - 3) = 7(21)
4*x - 4*3 = 147
4x - 12 = 147
4x = 147 + 12
x = 159/4
x = 39 3/4 (39.75)
(option C)
2008-12-17 2:49 pm
4/7 = 21/(x - 3)
4(x - 3) = 7(21)
4x - 12 = 147
4x = 159
x = 159/4 or 39 3/4
Answer: Option C: x = 39 3/4
Proof:
4/7 = 21/(159/4 - 3)
4/7 = 21/(159/4 - 12/4)
4/7 = 21/(147/4)
4/7 = 21(4/147)
4/7 = 84/147
4/7 = (84/21)/(147/21)
4/7 = 4/7
4(x - 3) = 7(21)
4x - 12 = 147
4x = 159
x = 159/4 or 39 3/4
Answer: Option C: x = 39 3/4
Proof:
4/7 = 21/(159/4 - 3)
4/7 = 21/(159/4 - 12/4)
4/7 = 21/(147/4)
4/7 = 21(4/147)
4/7 = 84/147
4/7 = (84/21)/(147/21)
4/7 = 4/7
2016-12-11 4:57 am
4/7 = 21/x-3 multiply the two sides by utilising x-3 (x-3) * 4/7 = 21 distribute (4x-12)/7 =21 4x - 12 = 147 4x = 159 x = 159/4 or 39.seventy 5 yet in any different case, turn each and each fraction over 7/4 = (x-3)/21 147/4 = x-3 147 / 4 = x - (12/4) 159/4 = x
2008-12-17 4:13 pm
Suppose you learn nothing else today remember that brackets MUST be used to present question correctly .As you have given it, question MUST be read as :-
4/7 + (21/x) - 3 and I am pretty sure that this is NOT what you mean ?
What you mean is :-
4 / 7 = 21 / (x - 3)
4x - 12 = 147
4x = 159
x = 159 / 4
x = 39 ¾
PS
Best wishes and remember the brackets !
4/7 + (21/x) - 3 and I am pretty sure that this is NOT what you mean ?
What you mean is :-
4 / 7 = 21 / (x - 3)
4x - 12 = 147
4x = 159
x = 159 / 4
x = 39 ¾
PS
Best wishes and remember the brackets !
2008-12-17 3:53 pm
4/7=21/x-3
4(x-3)/7=21
4x-12=147
4x=159
x=159/4
x=39 3/4
4(x-3)/7=21
4x-12=147
4x=159
x=159/4
x=39 3/4
2008-12-17 2:56 pm
4/7=21/x-3 Cross multiply
4x-12=147 Add 12
4x=159 Divide by 4
x= 39 3/4
Answer C
4x-12=147 Add 12
4x=159 Divide by 4
x= 39 3/4
Answer C
2008-12-17 2:50 pm
4/7=21/x-3
cross multiply
4x-12=147
4x=159
x=39 3/4
cross multiply
4x-12=147
4x=159
x=39 3/4
收錄日期: 2021-05-01 11:37:35
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081217064315AArbKUw