Answer:
Formula for nth term in Arithmetic sequences is:
where a is the first term, d is the common difference and n is the number of terms.
As per the statement:
The rule for the pattern is add 4.
As the first term in line says the first term i,e 7
common difference(d)= 7
As the Jenna number is 8th in line.
Series we get;
7, 11, .........
We have to find the 8th term.
n = 8, a = 7 and d = 4
Using above formula:
Therefore, 35 number should Jenna say.
Answer:
C
Step-by-step explanation:
Calculate AC using Pythagoras' identity in ΔABC
AC² = 20² - 12² = 400 - 144 = 256, hence
AC = = 16
Now find AD² from ΔACD and ΔABD
ΔACD → AD² = 16² - (20 - x)² = 256 - 400 + 40x - x²
ΔABD → AD² = 12² - x² = 144 - x²
Equate both equations for AD², hence
256 - 400 + 40x - x² = 144 - x²
-144 + 40x - x² = 144 - x² ( add x² to both sides )
- 144 + 40x = 144 ( add 144 to both sides )
40x = 288 ( divide both sides by 40 )
x = 7.2 → C