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Mathematics: Post your doubts here!

asadalam

asadalam

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2 Find the set of values of k for which the line y = kx − 4 intersects the curve y = x2 − 2x at two distinct points. [4]

From s09p1.
I get we have to equate the answer and then use the discriminant but after getting 2 and -6 how do you know what each inequality we need to put?
Like the answer is k>2 and k<-6
How do we get this part right?
 
Thought blocker

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asadalam said:
2 Find the set of values of k for which the line y = kx − 4 intersects the curve y = x2 − 2x at two distinct points. [4]

From s09p1.
I get we have to equate the answer and then use the discriminant but after getting 2 and -6 how do you know what each inequality we need to put?
Like the answer is k>2 and k<-6
How do we get this part right?
Click to expand...
kx - 4 = x^2 - 2x
x^2 - 2x - kx + 4 = 0
x^2 - x (2 + k) + 4 = 0
Use b^2-4ac = 0 (Discriminant = 0 as curve intersects at two distinct points)
k^2 + 4k + 4 - 16 = 0
hence, k > 2 and k < -6 :)
 
asadalam

asadalam

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Thought blocker said:
kx - 4 = x^2 - 2x
x^2 - 2x - kx + 4 = 0
x^2 - x (2 + k) + 4 = 0
Use b^2-4ac = 0 (Discriminant = 0 as curve intersects at two distinct points)
k^2 + 4k + 4 - 16 = 0
hence, k > 2 and k < -6 :)
Click to expand...
I figured it out till the end too,but where did you get the 2 and -6 from,and how do you work out what inequality sign goes with which?Can you solve on a paper and post a photo?
 
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Glory Hunter

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Thought blocker said:
Both parts are easy, but here is the explanation of part ii)
Find the total length from AC using sin rule
sin(1.2)/AC=sin(0.6)/5
AC=8.25
we know PC and AQ are 5 cm so
10-8.25=1.75
Click to expand...
thanx alot buddy i did but i did it by a long way i first found length of bd and then by are of triangle i found height then i assumed that cr=4.127 that was my prvious answer then 5- ans and *2 than i got 1.75 u r one is ,much easier thanx alot
 
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Glory Hunter said:
thanx alot buddy i did but i did it by a long way i first found length of bd and then by are of triangle i found height then i assumed that cr=4.127 that was my prvious answer then 5- ans and *2 than i got 1.75 u r one is ,much easier thanx alot
Click to expand...
That site is much of a HELP! I learn new ways outta PRACTICE! :)
You will come across one question of St. line, which is twisted, I know you will ask that as well, coz its all Ulta pulta method. :p
 
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RoOkaYya G

RoOkaYya G

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Faaiz Haque said:
3rd time posting this..


Can someone help me with this question please and explain.
Q9ii) http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w06_qp_1.pdf

And
Q5)http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w05_qp_1.pd
Click to expand...
Thought blocker said:
RoOkaYya G
HELP him, I forgot again. :/
Click to expand...

device the formula n make h subject of formula
using the formula for volume of the shape (cross sectional area * height)
replace h in volume
solve

QU 5 use similarity property find the measurements
 
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