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# Stuck on a C1 Question watch

1. I'm currently revising for my C1 exam in January and have come across a question that has really got me stumped. Any help wud be very much appreciated

Find in exact form the real solutions of the equation:

x^4 = 5x^2 + 14
2. Just say x^2 = z, then you should be able to solve for z and hence x.
3. x^4 - 5x^2 - 14 = 0
(x^2 - 5)^2 = 39
x^2 - 5 = +/- sqrt39
x^2 = +/- sqrt39 + 5
x = +/- sqrt( +/- sqrt39 + 5)
4. (Original post by Tut)
I'm currently revising for my C1 exam in January and have come across a question that has really got me stumped. Any help wud be very much appreciated

Find in exact form the real solutions of the equation:

x^4 = 5x^2 + 14
let y = x^2

y^2 = 5y + 14

y^2 - 5y - 14 = 0

(y - 7) (y + 2)

y = 7 or y = -2

x = sqrt 7
5. (Original post by Lord)
let y = x^2

y^2 = 5y + 14

y^2 - 5y - 14 = 0

(y - 7) (y + 2)

y = 7 or y = -2

x = sqrt 7
oops...
I really should have gotten that one right.
6. (Original post by Lord)
let y = x^2

y^2 = 5y + 14

y^2 - 5y - 14 = 0

(y - 7) (y + 2)

y = 7 or y = -2

x = sqrt 7
And -sqrt 7

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