Find x
4^(x+1) - 2^x = 3
Maths question
2006-11-24 4:12 am
回答 (3)
2006-11-24 4:21 am
✔ 最佳答案
4^(x+1) - 2^x = 32^(2x+2) - 2^x = 3
4*2^(2x) - 2^x = 3
4*(2^x)² - 2^x - 3 = 0
Let y = 2^x. Then,
4y² - y - 3 = 0
(4y+3)(y-1)=0
y = -3/4 or 1
So 2^x = -3/4 (Rejected since 2^x＞0) or 2^x = 1
2^x = 1
x = 0
Hope it helps! ^^
參考: Myself
2006-11-24 4:44 am
4^(x+1)-2^x = 3
4^x+4-2^x=3
2^x+4=3
2^x=-1
x=-1/2
4^x+4-2^x=3
2^x+4=3
2^x=-1
x=-1/2
2006-11-24 4:16 am
4^(x+1) - 2^x = 3
4x+4-2x=3
2x=-1
x=-1/2
4x+4-2x=3
2x=-1
x=-1/2
收錄日期: 2021-04-12 23:00:28
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