How do you evaluate #-4\sqrt { 245} - 3\sqrt { 5}#?

1 Answer
Jim G.
Sep 2, 2017

#-31sqrt5~~ -69.32" to 2 dec. places"#

Explanation:

#"using the "color(blue)"law of radicals"#

#•color(white)(x)sqrtaxxsqrtbhArrsqrt(ab)#

#"simplifying "-4sqrt245" using the above law"#

#=-4(sqrt(49xx5))#

#=-4(sqrt49xxsqrt5)#

#=-4(7sqrt5)=-28sqrt5#

#rArr-4sqrt245-3sqrt5#

#=-28sqrt5-3sqrt5larr" collect terms together"#

#=-31sqrt5~~ -69.32" to 2 decimal places"#

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