what is the best book for Pre-Calculus? i have missed pre-calculus knowledge in my school but i was good at maths, and now i am a computer science student, i am feeling bad being bad in maths, so i am looking for the best Pre-Calculus book, i love maths, i need the right well of precalculus books.  
 A: As a computer science student, you might also want to check out Knuth, Graham, and Patashnik Concrete Mathematics, which I consider to be absolutely indispensable for comp sci students. It's a very thorough book! Not necessarily recommended to replace Calculus, but provides the nuts and bolts of the basics in math that you'll want to master!
Major topics include:
Sums
Recurrences
Integer functions
Elementary number theory
Binomial coefficients
Generating functions
Discrete probability
Asymptotic methods

And more...
"This book introduces the mathematics that supports advanced computer programming and the analysis of algorithms. The primary aim of its well-known authors is to provide a solid and relevant base of mathematical skills - the skills needed to solve complex problems, to evaluate horrendous sums, and to discover subtle patterns in data. It is an indispensable text and reference not only for computer scientists - the authors themselves rely heavily on it! - but for serious users of mathematics in virtually every discipline."
"The book includes more than 500 exercises, divided into six categories. Complete answers are provided for all exercises, except research problems, making the book particularly valuable for self-study." 
A: I would recommend: David Cohen - Precalculus with unit circle trigonometry
It's a $1200$ pages book that covers quiet a lot of useful and interesting topics:


*

*Fundamentals.
Sets of Real Numbers. Absolute Value. Solving Equations (Review and Preview). Rectangular Coordinates. Visualizing Data. Graphs and Graphing Utilities. Equations of Lines. Symmetry and Graphs. Circles.

*Equations And Inequalities.
Quadratic Equations: Theory and Examples. Other Types of Equations. Inequalities. More on Inequalities.

*Functions.
The Definition of a Function. The Graph of a Function. Shapes of Graphs. Average Rate of Change. Techniques in Graphing. Methods of Combining Function. Iteration. Inverse Functions.

*Polynomial and Rational functions. Applications to optimization.
Linear Functions. Quadratic Functions. Using Iteration to Model Population Growth (Optional Section). Setting up Equations That Define Functions. Maximum and Minimum Problems. Polynomial Functions. Rational Functions.

*Exponential and Logarithmic functions.
Exponential Functions. The Exponential Function $y = e^x$. Logarithmic Functions. Properties of Logarithms. Equations and Inequalities with Logs and Exponents. Compound Interest. Exponential Growth and Decay.

*The Trigonometric functions.
Radian Measure. Trigonometric Functions of Angles. Evaluating the Trigonometric Functions. Algebra and the Trigonometric Functions. Right-Triangle Trigonometry.

*Graphs of the Trigonometric functions.
Trigonometric Functions of Real Numbers. Graphs of the Sine and the Cosine Functions. Graphs of $y = A \sin(Bx-C)$ and $y = A \cos(Bx - C)$. Simple Harmonic Motion. Graphs of the Tangent and the Reciprocal Functions.

*Analytical Trigonometry.
The Addition Formulas. The Double-Angle Formulas. The Product-to-Sum and Sum-to-Product Formulas. Trigonometric Equations. The Inverse Trigonometric Functions.

*Additional topic in Trigonometry.
Right-Triangle Applications. The Law of Sines and the Law of Cosines. Vectors in the Plane, a Geometric Approach. Vectors in the Plane, an Algebraic Approach. Parametric Equations. Introduction to Polar Coordinates. Curves in Polar Coordinates.

*Systems of equations.
Systems of Two Linear Equations in Two Unknowns. Gaussian Elimination. Matrices. The Inverse of a Square Matrix. Determinants and Cramer's Rule. Nonlinear Systems of Equations. Systems of Inequalities.

*Analytic Geometry.
The Basic Equations. The Parabola. Tangents to Parabolas (Optional). The Ellipse. The Hyperbola. The Focus-Directrix Property of Conics. The Conics in Polar Coordinates. Rotation of Axes.

*Roots of Polynomial equations.
The Complex Number System. Division of Polynomials. Roots of Polynomial Equations: The Remainder Theorem and the Factor Theorem. The Fundamental Theorem of Algebra. Rational and Irrational Roots. Conjugate Roots and Descartes' Rule of Signs. Introduction to Partial Fractions. More About Partial Fractions.

*ADDITIONAL TOPICS.
Mathematical Induction. The Binomial Theorem. Introduction to Sequences and Series. Arithmetic Sequences and Series. Geometric Sequences and Series. DeMoivre's Theorem.
Appendix 1: Using a Graphing Utility.
Appendix 2: Significant Digits and Calculators. 



[RV] I used this book in high school and absolutely loved it. It's
  very skimpy on proofs, and really should not be used for that sort of
  insight. However, in terms of understanding how to apply various
  mathematical concepts it's wonderful. It has a large number of graphs,
  examples, and easy reference tables. It covers all the algebra, trig,
  and cartesian geometry that any good high school math sequence should
  deal with. I have used it for years as a reference book (e.g., what
  exactly is Cramer's rule again...) Solutions to a number of the
  problems are in the back, and the problems are not entirely
  applications.

A: There is a FREE AND OPEN SOURCE book titled 'Precalculus' by Carl Stitz and Jeff Zeager. Its  quite detailed at close to 1000 pages. It is an ebook with no official hard copy published. Quality definitely is NOT lacking just because its free and open source. Its up there with the best in the market. Hope you find it useful. Link to the ebook pdf is below. 
http://stitz-zeager.com/szprecalculus07042013.pdf
A: If someone wants me to know a great book as you wanted, I'll suggest him "Modern Calculus", an old book written by R.A.Silverman. I don't know why; but I've got much more basic concepts in Calculus from the old books. This book makes an student a solid root in Calculus.
A: More often than not Amazon's search has got the best book listed first. For precalculus it's "The Complete Idiot's Guide to Precalculus". I guess the title is refering to the guy that named those books.
You could search on Google Books too, but their results are not listed by numbers of copies sold.
Also I have been told that Calculus On Manifolds is very popular among computer science students. From amazon:

This little book is especially concerned with those portions of
  ”advanced calculus” in which the subtlety of the concepts and methods
  makes rigor difficult to attain at an elementary level. The approach
  taken here uses elementary versions of modern methods found in
  sophisticated mathematics. The formal prerequisites include only a
  term of linear algebra, a nodding acquaintance with the notation of
  set theory, and a respectable first-year calculus course (one which at
  least mentions the least upper bound (sup) and greatest lower bound
  (inf) of a set of real numbers). Beyond this a certain (perhaps
  latent) rapport with abstract mathematics will be found almost
  essential.

A: Frank Ayres, First Year College Mathematics, Shaum's Outline
Based on how you describe yourself, think this is very efficient thing for you to study from.  In general Shaum's gets good response from students.  And for someone like you who is well into other courses but needs to go back and remediate a gap, it works great.  Very solid for self study with the answers and all included. And the writing is just enough to give you concepts but without drowning you in word soup.  Very practical drill book (I say that as a positive.)
I recommend an older used edition. Don't get a scan or electronic version either.
https://www.amazon.com/Theory-problems-first-college-mathematics/dp/B0007DPVM2
(copying link to older edition, but you can check newer edition for reviews if you want that.)
A: You might want to have a look at the following (peruse them at your favorite online book store).
Precalculus Mathematics in a Nutshell: Geometry, Algebra, Trigonometry, George F. Simmons
Pre-calculus Demystified 2/E, Rhonda Huettenmueller
Some other food for thought.
You may also want to look at actual calculus books at your local university library and see some of the topics you might need.
You might want to get and learn to use a Computer Algebra System. You want to learn to explore mathematics and ask all sort of what-if questions and also learn about programming.
Regards
A: Hi, this is my preference (not everyone will agree)
As no one (so far as I can see?) have recommended; I can say:

*

*$George\, F\,.\, Simmons\ Calculus\ With\ Analytic\ Geometry$ 2nd edition


*https://www.amazon.com/Calculus-Analytic-Geometry-George-Simmons/dp/0070576424
