IGCSE MATHS Doubts

[haris94]

okie
i hate simlifying so im sorry it took a while :/
i got the same thing as u so i must have done somat wrong but wait lemme check again.

k Thanks

[ksitna]

i see u;ve answered them ..

lol sorry....


right and i have no idea what i did wrong VIN help!!!

[haris94]

number 'n' , common diff. 'd' , first term 'a' and difference change 'c'is:


a+d(n-1)+c/2(n-1)(n-2)

try this wat was the sequence By the way ??

yea thats the formula i used
sequence is
4, 12, 24, 40...........

[ksitna]

so haris did it work?

[ksitna]

i got 2n2+2n-4
did i do it wrong?

[Vin]

i got 2n2+2n-4
did i do it wrong?

nop .. the sequence is wrong !! +@

wats the ans !!

[SoONa]

in d1 and 2
u nned the graph

u look at the points that are the least (4,4)
and the highest (6,6)
but first you have to make sure if it really is the highest and lowest
or u can solve it algebraically



VIN yes i think they are answered

yeah i got the points  is the final answer 18 n 27??  

[haris94]

yea i got it
*jumps in joy*  

umm no yours isnt right
this is what i did                                                                       4      12     24     40
                                                                                                 8      12     16
a+(n-1)d+0.5(n-1)(n-2)c                                                                   4       4
ok so "a" will be 4 (first term)
"d" will be first difference, that is 8
"c" is second difference thats is 4

so substitute and u get 2n²+2n

Thanks a lot for the fromula  

[the_grim_reaper]

You will get 2n^2+ 2n if simplified properly
                    1
see 4+(n-1)8+---(n-1)(n-2)4        
                    2                      
Cut 1/2 by 4 to make it 2.
so its 4+(8n-8)+(n-1)(n-2)2
now,  4-8+8n + (n^2-2n-n+2)2
no its -4+8n+ (n^2-3n+2)2
which is -4+8n +2n^s-6n+4
finally, 2n^2+8n-6n-4+4
which is 2n^2+2n+0= 2n^2 + 2n
By the way, the formula is correct......

[princess12]

1,3,6,10 write next 4 sequence fast please  
 
urgently fast reply plaese  

[Shazizzzle]

No, salooo!

[haris94]

1,3,6,10 write next 4 sequence fast please  
 
urgently fast reply plaese  

  +2  +3   +4      +5       +6     +7
1    3    6      10       15      21      28

and so on

[Vin]

1      3       6     10      15     21     28     36
      2     3     4       5       6         7        8    (add these nos to previous ones)
          1     1  (add 1 to 4)  

[ksitna]

yeah i got the points  is the final answer 18 n 27??  

yes thts correct

[princess12]

thanks