Step-by-step explanation:
x = the number
2x - 25 = x
2x = x + 25
x = 25
There are 5 letters
there are 5 possibilities for the first letter, and 4 possibilities for the second letter after the first letter is used up
so 5 * 4 = 20 possibilities
A half-life of the isotope is 15 days and at start its mass is 32 g.
A table:
t: m:
0 32 g
15 16 g
30 8 g
45 4 g
60 2 g
75 1 g
In the first column is used an arithmetic sequence ( a 1 = 0, d = 15 ).
In the second column is used a geometric sequence ( a 1 = 32, r = 1/2 )
Step-by-step explanation:
3 tan 2x - 4 tan 3x = tan² 3x * tan 2x
3 (tan 2x - tan 3x) = tan 3x + tan² 3x * tan 2x
= tan 3x (1 + tan 3x * tan 2x)
3 (tan 2x - tan 3x)/(1 + tan 3x * tan 2x) = tan 3x
3 * (- tan x) = tan 3x
-3tanx = (3 tan x - tan³ x) / (1 - 3 tan² x)
3 - tan² x = - 3 + 9 tan² x
tan x = + √3 /√5 or - √3/√5
