Originally Posted by
exclusiive hey, i have a question and also the answers,
ive worked it out and have the first answer but i just get my head round to how the 2nd answer is....
this is the q..
given that y=ax^n + 3, that y=4.4 when x=10 and y=12.8 when x=100, find the value of 'n' and 'a'
the 2 answers are 0.845 & 0.2
this is my working out for the first answer....
y = ax^n +3 => y=4.4, x=10
4.4 = a10^n + 3
a = (4.4 - 3) / 10^n
= 1.4/10^n
y = 12.8, x = 100
12.8 = a100^n + 3
12.8 = (1.4/10^n) x 100^n + 3
so 100^n = 10^2n
12.8 = (1.4/10^n) x 10^2n + 3
9.8 = 1.4 x 10^n
10^n = 7
log7 = log10^n
n = (log7)/(log10)
= 0.845
i am so sorry if this is long, im currently in 6th form, studying IB
& in order for me to learn, i like having the steps in my working out rite...
so how would i get to the answer 0.2?