Qualification > Math
Additional Math Help HERE ONLY...!
vanibharutham:
Real Roots
First, lets establish what roots are :P
If we are given the equation
x2-4x+4 = 0
you might straight away know that the answer is
(x-2)2=0
x = 2
But that x = 2 is a root.... it is where the curve crosses the axis
REAL ROOTS mean that the equation has roots that real numbers
and there is only two possible ways for it to have real roots
EITHER - (USING ax2+bx+c)
b2 > 4(a)(c)
OR
b2 = 4(a)(c)
If we were given another equation
Lets say
x2 - 15x + 31 = 0
And we were asked to find what type of roots it had
Then simply:
Find b2 and find 4ac
b2 = (-15)2 = 225
4ac = 4(1)(31) = 124
Here,
b2 > 4ac
And hence we have real roots
Padapop:
vanib is like a maths teacher ahaha.
Ok question on intergrating virtually anything:
if intergrating sin/cos like we had to in 12 EITHER in paper 1, i think i got the area wrong because i forgot he +c, gosh my area was like 0 ahaha failed. I do remember my answer to the previous question was 1. something and 7. something.
And intergrating sin/cos/exponential/normal gets kinda confusing sometimes.
archangel:
help needed for permutation combination ???
i suck at the ones which like digits and how many numbers can be formed :-\
like this one:
Each of seven cards has on it one of the digits 1,2,3,4,5,6,7; no two cards have the same digit.
Four of these cards are selected and arranged to form a 4-digit number.
i) How many different 4-digit numbers can be formed this way?
ii) How many of these 4-digit numbers begin and end with an even digit?
for my ans:
i) i wrote 4! x 7
but the answer is 840... help? :-[
ii) i wrote 2 x 4 x 3 x 3
but the answer is 240.... ahhh :-[
shan2391:
4 the first 1:
leave spaces as there r 4digits to b made _*_*_*_
now the first space has sven options so 7*_*_*_
as we have used 1 option or digit we r left with 6 so 7*6*_*_
as we have used 2 options or digits we r left with 5 so 7*6*5*_
as we have used 3 options or digits we r left with 4 so 7*6*5*4=840
got it
divineobsidian:
yea what shan said or you can do 7P4 if you have that on your calculator
unfortunately i get 120 on the 2nd question ,not a lot of help but meh. ???
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