Surds C1
Maths and statistics discussion, revision, exam and homework help.
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Surds C1Expand and simplify (7 + 3ROOT 2)(5 − 2 ROOT2).
I got the answer to be -11 but i'm not tooo sure !
Also, does anyone know how to explain (iv) ,the last bit of this question, from the JAN2012 C1 OCREMEI past paper? Thaks everybody!
(iii) Show that, where the line y = 2x + k intersects the circle,
5x^2 + (4k − 4) x + k^2 − 16 = 0. [3]
(iv) Hence find the values of k for which the line y = 2x + k is a tangent to the circle. -
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Re: Surds C1(Original post by alex7892)
Expand and simplify (7 + 3ROOT 2)(5 − 2 ROOT2).
I got the answer to be -11 but i'm not tooo sure !
Also, does anyone know how to explain (iv) ,the last bit of this question, from the JAN2012 C1 OCREMEI past paper? Thaks everybody!
(iii) Show that, where the line y = 2x + k intersects the circle,
5x^2 + (4k − 4) x + k^2 − 16 = 0. [3]
(iv) Hence find the values of k for which the line y = 2x + k is a tangent to the circle.
Show your working. -
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Re: Surds C1(Original post by alex7892)
Also, does anyone know how to explain (iv) ,the last bit of this question, from the JAN2012 C1 OCREMEI past paper? Thaks everybody!
(iii) Show that, where the line y = 2x + k intersects the circle,
5x^2 + (4k − 4) x + k^2 − 16 = 0. [3]
(iv) Hence find the values of k for which the line y = 2x + k is a tangent to the circle.
We know a tangent intersects the circle at only one point, hence the quadratic,
, will have repeated roots.
So solve,
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Re: Surds C1No.(Original post by alex7892)
Sorry looks like I made a mistake. Would the answer be:
35-14root5+15root2-6root10 ?
Remember,
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Re: Surds C1Quadratics have the form
a,b and c are the coefficients of each term in the general quadratic equation. So, 'a' is whatever comes before an x^2, 'b' is whatever comes before an 'x', and 'c' is anything that doesn't have an 'x' in it.
(extra: technically, c is the coefficient of x^0, but as x^0 = 1 theres no need to write it.)Last edited by F1Addict; 11-05-2012 at 15:26. -
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Re: Surds C1(Original post by alex7892)
Oh so sorry, I posted the wrong question, and my answer was for the other question haha I mean (7+3root2) (5-2root5)
Sorry!! And what would A, and C be then that is confusing
By the way, are you sure you have typed out the right question now? -
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Re: Surds C1Yes, this is correct(Original post by alex7892)
Sorry looks like I made a mistake. Would the answer be:
35-14root5+15root2-6root10 ?
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Re: Surds C1I answer a lot of questions on the maths forum, so it is difficult to keep track of the people, except very active members.(Original post by alex7892)
Thanks a lot Raheem going to personal rep you in a minute, always sorting out my maths problems aren't you! lol
