How do I solve the equation cos^2(x) - 4*cos(x) + (7 / 4 ) < 0?

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The equation cos^2(x) - 4*cos(x) + (7 / 4) < 0 can be approached by factoring or using the quadratic formula. By substituting z = cos(x), the problem simplifies to solving a quadratic inequality in terms of z. The discussion also highlights the importance of posting in the correct forum category, as the original post was mistakenly placed in "other Sciences." The issue was resolved successfully, and the thread was moved to the appropriate Precalculus Mathematics section. Proper categorization enhances the chances of receiving relevant assistance for math-related queries.
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[SOLVED] Math - solving equation

Homework Statement



x belongs to Real numbers

Homework Equations



solving on paper
cos^2(x) - 4*cos(x) + (7 / 4 ) < 0


The Attempt at a Solution



no worthly attemps yet
 
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why don't you factorise it by using the completing the square thing or the ((-b)+or- (root(b^2) - 4ac) )/2a
...i think?
 
To follow up on sara_87's post, let z = Cos(x). Now you have a quadratic equation (inequality) which you can solve for z.

Next time you have a similar question please post it under Pre-calculus Math.
 
Why in the world is this in "other Sciences"?
 
well, i didnt see simply 'math' section , only saw 'calculus math' , didnt see 'Precalculus Mathematics' since i didnt have much time to post, sorry for wrong section. Next time ill know where to post for these types of questions

and btw, thanks for your help, resolved it easily now
 
Last edited:
Thread moved to Precalc Math.
 

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