Equations Reducible to Quadratics (1 Viewer)

[Lukybear]

How to solve this question using subsitution:



Thanks

 

[gurmies]

Not sure how to do it with substitution, but there is another way. x = 4

 

[jet]

I can't think of a way to reduce it but with trig substitutions. If I'm thinking the same as gurmies, you just subtract the sqrt(x) and square both sides.

 

[Lukybear]

Perhaps trig subs is far beyond me. Under which general topic is that under?

O I see. It was in the Cambridge book, under the heading of Equations reducible to quadratics. THus I assumed subsitution was need. THanks for advice Jetblack and gurmies.

 

[Timothy.Siu]

How to solve this question using subsitution:



Thanks

let x=5tan²@

root5. |sec @|+root5. tan@=5
(1+sin@)/cos@=root5
sin@-root5cos@=-1
root6. sin(@-tan^-1(root5))=-1
sin(@-tan^-1(root5))=-1/root6
@=sin^-1 (-1/root6) +tan^-1 root5

x=5tan [sin^-1 (-1/root6) +tan^-1 root5]
=4

lol...