How do you simplify #(sqrt7-2sqrt2)(sqrt7+3sqrt2)#?

1 Answer
Don't Memorise
Jul 6, 2015

#=color(blue)(sqrt14 -5#

Explanation:

#color(blue)((sqrt7 -2sqrt2)) . (sqrt7 +3sqrt2)#

#=color(blue)(sqrt7) . (sqrt7 +3sqrt2) - color(blue)(2sqrt2).( sqrt7 +3sqrt2)#

#=(color(blue)(sqrt7).sqrt7 + 3sqrt2. color(blue)(sqrt7) )-color(blue)(2sqrt2).sqrt7 -color(blue)(2sqrt2 ). 3sqrt2#

#=7 + 3sqrt14 -2sqrt14 - 6sqrt4#

#=7+sqrt14 -(6.2)#
#=7+sqrt14 -12#
#=color(blue)(sqrt14 -5#

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