急急急 數學題

1a)2log x =3log y
logx=3logy/2
logx=logy^3/2
x=y^3/2
1b)logxy=1/2
logxy=log(10/100)
xy=10/100
x=1/10y
2)x^3+x^2-8x-12
=x^3+(x+2)(x-6)
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3a)4^x=50
1og4^x=log50
xlog4=log50
x=log50/log4
x=2.82(corr. to 3 sig. fig.)
3b)log(3x-5)=2
log(3x-5)=log100
(3x-5)=100
3x=105
x=35
4)5.3=logA+2.24
3.06=logA
10^3.06=A
so,A is 10^3.06

1a) 2log x =3log y

log x^2 = log y^3

x^2 = y^3

x = y^(3/2)

1b) log xy = 1/2

log xy = log 10^(1/2)

xy = 10^(1/2)

x = 10^(1/2) / y

2) x^3+x^2-8x-12

= x^3 - 27 + x^2 - 8x + 15

= (x - 3)(x^2 + 3x + 9) + (x - 3)(x - 5)

= (x - 3)(x^2 +3x + x + 9 - 5)

= (x - 3)(x + 2)(x + 2)

= (x - 3)(x + 2)^2

3a) 4^x = 50

log 4^x = log 50

x log 4 = log 50

x = log 50 / log 4

x = 2.82 ( corr.to.3 sig.fig)

3b) log(3x-5)=2

log(3x-5) = log 100

3x - 5 = 100

3x = 105

x = 35

4) M=log A+2.24

5.3 = log A + 2.24

3.06 = log A

10^3.06 = A

A = 1148.2(corr.to.1.d.p.)

2008-01-03 07:06:58 補充：
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