# alevel math

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#1
can anyone tell me how to answer this problem??
Fiona and lawrence both save money
fiona saves £50 in the first month and then increases the amount she saves by £10 per month after
lawrence saves £50 in the first month and then increases the amount he saves by 10% per month thereafter
write down expressions for the total amount saved by fiona and lawrence after x months
can anyone also tell me which topic this comes under thanks
0
1 month ago
#2
sequences and series! Fionas savings form a sequence 50+10(x-1), where x is the number of months (as 50=month 1, etc). Laurance’s grows exponentially and forms a sequence 50x1.1^(x-1), as he increases by 10% each month. Their total is 50+10(x-1)+50•1.1^(x-1) , which is 50(1+0.2(x-1)+1.1^(x-1)). Sorry this is rushed and it may be wrong, but you’re looking at sequences and series!!
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#3
(Original post by Hannahthemanzana)
sequences and series! Fionas savings form a sequence 50+10(x-1), where x is the number of months (as 50=month 1, etc). Laurance’s grows exponentially and forms a sequence 50x1.1^(x-1), as he increases by 10% each month. Their total is 50+10(x-1)+50•1.1^(x-1) , which is 50(1+0.2(x-1)+1.1^(x-1)). Sorry this is rushed and it may be wrong, but you’re looking at sequences and series!!
thank you very much for the explanation. Really appreciate you giving the time to answer. one thing, the reason you used x-1 is because you already accounted for the first month
0
1 month ago
#4
Yes exactly that, anything to the power of 0 is 1, so if you use x-1 the first month will give you 50; the same as if you have 50+10(x-1), when x= 1, you get 50! Hope that’s helped

(Original post by nomen552)
thank you very much for the explanation. Really appreciate you giving the time to answer. one thing, the reason you used x-1 is because you already accounted for the first month
0
#5
(Original post by Hannahthemanzana)
Yes exactly that, anything to the power of 0 is 1, so if you use x-1 the first month will give you 50; the same as if you have 50+10(x-1), when x= 1, you get 50! Hope that’s helped
omgg yess it really helped thanks soo much!!!
1
1 month ago
#6
You’re welcome! Any time
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