BC=10, AC=x, and AB=2x-21. Solve for x ,and find the length of AB.
1 answer:
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Answer:
= 1
Step-by-step explanation:
The n th term of an arithmetic progression is
= a + (n - 1)d
where a is the first term and d the common difference
use the 9 th term and 7 th term to find a and d
= a + 8d =
→ (1)
= a + 6d =
→ (2)
Subtract (2) from (1) term by term
2d = ⇒ d =
Substitute this value into (2) and solve for a
a + =
a = -
=
Hence
=
+
= 1