i a man even number beetween 50 and 99 i am a multiple of 9 my tens digit is 5 more than my units digit
1 answer:
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Answer:
b. an = 2 • (-3)^(n - 1)
Step-by-step explanation:
Before we test a solution or two, we can easily discard most of them.
We see the values alternate of signs (-5 for the 2nd term and +162 for the 5th term)... so the progression factor has to be negative (in order to alternate sign). <u>That already excludes answers A and C.</u>
Normally, a geometric progression has the (n-1) exponent, not (n+1), so our chances seem to be better with B.
We can test both D and B with n = 2, to obtain -6
Let's test answer D before:
The result is -54, not -6... so it's not the right result.
Let's test answer B then:
Right! Let's verify with n=5 to get 162:
Confirmed, answer is B. an = 2 • (-3)^(n - 1)
Answer:
Therefore either a:b = 5:4 or a:b=-5:4
Step-by-step explanation:
ax²-5bx+4a=0
Since the quadratic equation has two real root.
Then b²-4ac>0
Here a= a , b= -5b and c=4a
∴(-5b)²-4.a.4a=0
⇔25b²=16a²
⇔5b=±4a
Therefore either a:b = 5:4 or a:b=-5:4