What is Square root of 2 - square root of 8 + 5 square root 18?

1 Answer
Don't Memorise
Jun 2, 2015

#sqrt2 - sqrt8 +5sqrt18#

  • #sqrt8 = color(blue)(2sqrt2#
  • #sqrt18 = color(red)(3sqrt2#
    # 5sqrt18 = 5 . color(red)(3sqrt2) = color(red)(15sqrt2#

rewriting the expression as:

#sqrt2 - color(blue)(2sqrt2+ color(red)(15sqrt2#

#(15sqrt2 - 2sqrt2 = 13sqrt2)#

#=sqrt2 + 13sqrt2#
#=color(green)(14sqrt2#
# approx color(green)(19.796#

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