Answer:
2n - 11
Step-by-step explanation:
Note there is a common difference d between consecutive terms of the sequence, that is
d = - 7 - (- 9) = - 5 - (- 7) = - 7 + 9 = - 5 + 7 = 2
This indicates the sequence is arithmetic with n th term
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Here a₁ = - 9 and d = 2, thus
= - 9 + 2(n - 1) = - 9 + 2n - 2 = 2n - 11
Answer:
Height of fir tree = 9 meters
height of pine tree= 12 meters
Step-by-step explanation:
The combined height of one fir tree and one pine tree is 21 meters. The height of 4 fir trees stacked on top of each other is 24 meters taller than one pine tree.
Let x be the height of fir tree and y be the height of pine tree
Subtract x from both sides
height of 4 fir trees = pine tree +24
Substitute 21-x or y in the above equation
Add x on both sides
Divide by 5 on both sides
x=9
Now plug in 9 for x and find out y
y=12
Height of fir tree = 9 meters
height of pine tree= 12 meters