3^(x+2)=5^2x what is x?

2009-03-04 7:18 am
i have simplified it, but it needs to be answered to 2 decimal places

回答 (4)

2009-03-04 8:16 am
✔ 最佳答案
3^(x+2)=5^2x
ln3^(x+2)=ln5^(2x)
(x+2)ln(3)=2xln(5)
3(x+2)=10x
3x+6=10x
3x-10x=-6
-7x=-6
x=6/7 answer//

another solution

(x+2)ln3=2xln5
xln3+2ln3=2xln5
xln3-2xln5=-2ln3
x(ln3-2ln5=-2ln3
......-2ln3..........-2ln3........
x=------------ =.. -------------
...(ln3-2ln5).....(ln3-ln5^2)

......-2ln(3)
x=-------------- answer//
....ln(3)-ln(25)
2009-03-04 9:39 am
3^(x + 2) = 5^(2x)
log[3^(x + 2)] = log[5^(2x)]
(x + 2)log(3) = (2x)log(5)
(x)log(3) + 2log(3) = (2x)log(5)
(x)log(3) - (2x)log(5) = -2log(3)
x[log(3) - 2log(5)] = -2log(3)
x = -2log(3)/[log(3) - 2log(5)]
2009-03-04 7:40 am
-(x+2)log3=2xlog5
-x+2/2x=1.465
-x+2=2.93x
-x=2/1.93=1.0363
2009-03-04 7:28 am
(x+2)log3=2xlog5
x+2/2x=1.465
x+2=2.93x
x=2/1.93=1.0363


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