標題:

有d數學問題~20點!!

發問:

是咁的,有d數學唔識做。 (請逐步例明所有步驟。) 1:7(d-3)-2d=9 2:10k-3(2-5k)=44 3:4(v-8)+3(v+7)=24 4:3(r+2)+2(r-4)=18 5:5(u-3)-2(u+5)=11 6 :2(c+7)-4(c-3)=10 20點是辛勞者的禮物~~~ 更新: 講錯左,是列明步驟。

最佳解答:

1. 7(d - 3) - 2d = 9 7d - 21 - 2d = 9 5d - 21 = 9 5d = 30 d = 6 2. 10k - 3(2 - 5k) = 44 10k - (6 - 15k) = 44 10k - 6 + 15k = 44 25k - 6 = 44 25k = 50 k = 2 3. 4(v - 8) + 3(v + 7) = 24 4v - 32 + 3v + 21 = 24 7v - 11 = 24 7v = 35 v = 5 4. 3(r + 2) + 2(r - 4) = 18 3r + 6 + 2r - 8 = 18 5r -2 = 18 5r = 20 r = 4 5. 5(u - 3) - 2(u + 5) = 11 5u - 15 - (2u + 10) = 11 5u - 15 - 2u - 10 = 11 3u - 25 = 11 3u = 36 u = 12 6. 2(c + 7) - 4(c - 3) = 10 2c + 14 - (4c - 12) = 10 2c + 14 - 4c + 12 = 10 -2c + 26 = 10 -2c = -16 c = 8

其他解答:

1. 7(d - 3) - 2d = 9 7d - 21 - 2d = 9 5d - 21 = 9 5d = 30 d = 6 2. 10k - 3(2 - 5k) = 44 10k - (6 - 15k) = 44 10k - 6 + 15k = 44 25k - 6 = 44 25k = 50 k = 2 3. 4(v - 8) + 3(v + 7) = 24 4v - 32 + 3v + 21 = 24 7v - 11 = 24 7v = 35 v = 5 4. 3(r + 2) + 2(r - 4) = 18 3r + 6 + 2r - 8 = 18 5r -2 = 18 5r = 20 r = 4 5. 5(u - 3) - 2(u + 5) = 11 5u - 15 - (2u + 10) = 11 5u - 15 - 2u - 10 = 11 3u - 25 = 11 3u = 36 u = 12 6. 2(c + 7) - 4(c - 3) = 10 2c + 14 - (4c - 12) = 10 2c + 14 - 4c + 12 = 10 -2c + 26 = 10 -2c = -16 c = 8

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