## Wednesday, October 28, 2009

### GMAT/CAT PREPARATION EMAIL COURSE DAY 13

`You must be having a good understanding of concepts of surds and indices to solve the problems faster in CAT ..http://catdumps.blogspot.com/2009/03/cat-gmat-gre-mba-index-if-m-is-positive.htmlHere are the Laws of SURDS AND INDICES http://catdumps.blogspot.com/2009/03/laws-of-surds-and-indices.htmlMultiplying and DividingTo multiply powers with the same base, keep the same base and add the exponents   3   5   3+5   8b X b = b   = bTo divide powers with the same base, keep the same base and subtract the exponents  10    8     10-8       2b   / b   = b        = bRaised Powers to PowersTo raise a power to a power, multiply the exponents:   3 5    3x5      15(b  )  = b      = bNegative PowersA number raised to a negative exponent is simply the reciprocal of that number raised to the corresponding positive exponent. -32   =  1 / 2^3  =   1 /8          Simplifying Roots             To simplify a square root, factor out the perfect squares under the radical, remove the perfect squares and put the result in front: __    ____   __      __        __V20 = V4X5 = V4   X  V5    = 2 V5Adding and Subtracting RootsYou can add or subtract radical expressions when the part under the radicals is the same   __     __      __2 V6 + 3 V6  = 5 V6Don't try to add or subtract when the radicals are different.  You cannot simplify expressions like:                ___           __                     ___      ___          2  V 5     +  3  V 6  {is not equal to  5V 6  or 5V 6   }Multiplying and Dividing RootsThe product of square roots is equal to the square root of the product: __    __     ______     __V 5 x V3  =  V5 X 3  =  V15The quotient of square roots is equal to the square root of the quotient: __   __      ____      ___V8  /V2   =  V8/2   =  V 4   =2`