Answer: 40
Step-by-step explanation:
Answer:
x=-7/9
y = 12/9
Step-by-step explanation:
6x + 2y = -2
3x - 2y = -5
9x = -7 (-2y and +2y eliminated)
x = -7/9
if 3x -2y = -5 then
3 ×(-7/9) -2y =-5➡
-21/9 -2y = -5➡
-2y = -5 + 21/9
-2y = -24/9
Answer:
Step-by-step explanation:
For a first order decay, fraction remaining = 0.5n where n = number of half lives elapsed.
fraction remaining = 55% = 0.55
0.55 = 0.5n
log 0.55 = n log 0.5
-0.2596 = -0.301 n
n = 0.8625 = # of half lives elapsed
0.8625 half lives x 2.5 billion years/half live = 2.16 billion years have elapsed = age of the rock
b) 0.15 = 0.5n
log 0.15 = n log 0.5
-0.824 = -0.301 n
n = 2.74 half lives
2.5 billion years/half life x 2.74 half lives = 6.85 billion years = age of rock
An integer is a whole number, and a decimal is not a whole number, it's like a fraction.
