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You are given that f(x) = x^3  19x + 30
1.) Calculate f(0) and f(3). Hence write down a factor of f(x).
Thanks.
 one year ago
 one year ago
You are given that f(x) = x^3  19x + 30 1.) Calculate f(0) and f(3). Hence write down a factor of f(x). Thanks.
 one year ago
 one year ago

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mukushlaBest ResponseYou've already chosen the best response.1
can u evaluate f(0) and f(3) ?
 one year ago

headgeBest ResponseYou've already chosen the best response.1
What does evaluate mean?
 one year ago

headgeBest ResponseYou've already chosen the best response.1
Hmmm hang on. Do you mean put them into the f(X)= thing?
 one year ago

HeroBest ResponseYou've already chosen the best response.0
Evaluate means to do this: f(x) = x^3  19x + 30 f(0) = (0)^3  19(0) + 30 = ? f(3) = (3)^3  19(3) + 30 = ?
 one year ago

headgeBest ResponseYou've already chosen the best response.1
Yes ok Ill have a go at that and tell you what I got thanks.
 one year ago

headgeBest ResponseYou've already chosen the best response.1
Right for f(0) I got 30 and the next one 0
 one year ago

headgeBest ResponseYou've already chosen the best response.1
Did it again and got 0 again.
 one year ago

HeroBest ResponseYou've already chosen the best response.0
f(3) = (3)^3  19(3) + 30 = 27  57 + 30 = 30 + 27  57 = 57  57 = 0 OK
 one year ago

headgeBest ResponseYou've already chosen the best response.1
Yes!! So now I have two more questions. Are you up for helping?
 one year ago

headgeBest ResponseYou've already chosen the best response.1
Wait what is the 'hence write down the factor of f(x)' bit?
 one year ago

HeroBest ResponseYou've already chosen the best response.0
If you calculated f(3) = 0, then (x3) is a factor
 one year ago

headgeBest ResponseYou've already chosen the best response.1
:) I remeber that now. The 0 ones it is.
 one year ago

headgeBest ResponseYou've already chosen the best response.1
(ii) Find p and q such that f(x) = (x2)(x^2 + px +q). How does one go about this?
 one year ago

headgeBest ResponseYou've already chosen the best response.1
@karatechopper @myininaya
 one year ago

CoolsectorBest ResponseYou've already chosen the best response.0
(x2)(x^2 + px +q) = x^3 +px^2 +qx 2x^2 2px 2q = x^3 +(p2)x^2 +(q2p)x  2q and the orig is x^3  19x + 30 so we know that p2 should be 0 and q2p should be 19 and 2q should be 30 can you answer now ?
 one year ago

headgeBest ResponseYou've already chosen the best response.1
Wait....Where has that big line came from? ohhh you timesed out the brackets! Ok wait a min.
 one year ago

headgeBest ResponseYou've already chosen the best response.1
I get it up to when you start saying the so we know p2=0 bit. I dont know how we know that.
 one year ago

CoolsectorBest ResponseYou've already chosen the best response.0
ok you see we have a term (p2)x^2 but in the general equation we dont have x^2 at all .. so we have to make it disappear .. we do this by saying p2 = 0
 one year ago
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