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Mathematics 16 Online
zarkam21:

Help

zarkam21:

1 attachment
Vocaloid:

oh wait

Vocaloid:

it's recursive, so you would start with a1 = 2 then apply the rule, which tells you to multiply the term by 3 and subtract 1 to get the next term

Vocaloid:

then take the result from that operation and then find the next term using the same rule

Vocaloid:

recursive formulas stink but thankfully we don't use these very often

zarkam21:

a1=2 a2=5 a3=14 a4=41 a5=122

Vocaloid:

good

Vocaloid:

so for 9 you want to write an arithmetic equation to solve for d

Vocaloid:

an = a1 + (n-1)d an = 11 a1 = 2 n = 4 solve for d

zarkam21:

d=3

Vocaloid:

awesome, now we use the sum formula

zarkam21:

okay

Vocaloid:

|dw:1510377993846:dw|

Vocaloid:

since we want n = 50 we will need to find a50 first

Vocaloid:

use this: an = a1 + (n-1)d to find an when n = 50, keeping the same a1 and d value as before

zarkam21:

149/50

Vocaloid:

a50 = 2 + (50-1)3 = ?

zarkam21:

297

Vocaloid:

ah think I see what the misunderstanding is the 50 in a50 is not treated like a number, it's just a label

zarkam21:

149

Vocaloid:

good, 149

Vocaloid:

now we go back to our sum formula

Vocaloid:

|dw:1510378518379:dw|

Vocaloid:

then find sn using these values

zarkam21:

3775

Vocaloid:

awesome, that's the final answer

Vocaloid:

for 10, this is what we are given: 3x + 2y = 14 2x - 4y = 4 start by doubling the first eqution

zarkam21:

okay

Vocaloid:

then, you should be able to eliminate y by adding the equations together

zarkam21:

wait by doubling do you mean 6x+4y=28

Vocaloid:

yes

Vocaloid:

since there's +4y on the top and -4y on the bottom these cancel when you add the equations

zarkam21:

12x=112

Vocaloid:

6x+4y=28 2x - 4y = 4 start by adding the x terms. 6x + 2x = ?

zarkam21:

oh we are adding I thought we were multiplying

zarkam21:

x=4

Vocaloid:

as a general rule you can multiply equations by a constant, but not multiply the equations together

Vocaloid:

yes, x = 4

Vocaloid:

now solve for y 2x - 4y = 4 when x = 4

zarkam21:

y=1

Vocaloid:

good so (4,1) = your ans

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