Log Rules
FOIL
Solve for X
Logarithms
Solving Log Equations
100

Expand as a sum and/or difference of logarithms:

log3(8/x)

log3(8)-log3(x)

100
(x + 1) (x + 2)
x2 + 3x + 2
100
Solve for x: x + 2 = 10
x = 8
100

Rewrite as a corresponding exponential equation: log7(1/49)=-2

7-2=(1/49)

100

log4x=7/2

128

200

Expand as a sum and/or difference of logarithms:

logb(xz3)

logb(x)+3logb(z)

200
(x - 4) (x + 3)
x2 - x - 12
200
Solve for x: 3x - 2 = 10
x = 4
200
Rewrite as a corresponding exponential equation:

log2(128)=7

27=128

200

log4x=-1

1/4

300

Rewrite as a single logarithm:

5log(2) + 3log(x)

log(32x3)

300
(2x + 1) (3x + 4)
6x2 + 11x + 4
300
Solve for x: 2x + 3 = x - 6
x = -9
300
Rewrite as a corresponding logarithmic equation:

54=625

log5625=4

300

log4(x-3)=-1

13/4

400

Rewrite as a single logarithm:

3log(5) - 1log(x)

log(125/x)

400
(4x - 3) (2x + 3)
8x2 + 6x - 9
400
Solve for x: 3x + 6 = x + 10
x = 2
400

Write as a corresponding logarithmic equation:

4-3=(1/64)

log4(1/64)=-3

400

4log7(x-7)=12

350
500

Rewrite as a single logarithm:

5log(x) - 2log(x2+1) + 2log(x-1)

logx5(x-1)2/(x2+1)2

500
(3x - 5) (3x - 4)
9x2 - 27x + 20
500

Solve for x: x2 - 5 = 20

x = 5

500

Rewrite as a corresponding exponential equation:

log9(729)=3

93=729

500

6+7log9x=20

81

M
e
n
u