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.
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.
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, 5x2+(4k−4)x+k2−16=0., will have repeated roots. So solve, b2−4ac=0
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
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.)
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
(7+32)(5−25)=−11
By the way, are you sure you have typed out the right question now?