X^2 - 25 is a difference of squares which has a special factorization.
In general, a^2 - b^2 = (a + b)(a - b)
x^2 - 25 = 0
(x + 5)(x - 5) = 0
x + 5 = 0 or x - 5 = 0
x = -5 or x = 5
Answer is <span>a) line BC is congruent to line CD
this is not true
BC should be </span>congruent to line EC, not CD
Might have to experiment a bit to choose the right answer.
In A, the first term is 456 and the common difference is 10. Each time we have a new term, the next one is the same except that 10 is added.
Suppose n were 1000. Then we'd have 456 + (1000)(10) = 10456
In B, the first term is 5 and the common ratio is 3. From 5 we get 15 by mult. 5 by 3. Similarly, from 135 we get 405 by mult. 135 by 3. This is a geom. series with first term 5 and common ratio 3. a_n = a_0*(3)^(n-1).
So if n were to reach 1000, the 1000th term would be 5*3^999, which is a very large number, certainly more than the 10456 you'd reach in A, above.
Can you now examine C and D in the same manner, and then choose the greatest final value? Safe to continue using n = 1000.
