- Messages
- 66
- Reaction score
- 20
- Points
- 18
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_qp_1.pdf
Please help me solve qn no. 8 (i & ii).. an explanation will be appreciated.
Thanks!
f(x) = a+bcos 2x
f(0)=−1
=> a + bcos 2(0) = -1
Solve cos 2(0) in radian mode.
=> a + b = -1
and f(π/2) = 7
=> a + bcos 2(π/2) = 7
=> a - b =7
Solve them as simultaneous equations.
a + b = -1
a - b =7
a will be 3 and b -4.
Part ii)
y would be 0 when the curve intersects the x axis.
Putting the values of a and b found in i, the equation becomes
=> 3 - 4cos2x
And because y=0
3 - 4cos2x = o
I guess u can solve the rest.
Hope I helped!