How do you multiply #-4\sqrt { 15} \cdot - 5\sqrt { 18}#?

Question

502 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-05-22T22:59:53

See a solution process below:

First, rewrite this expression as:

#(-4 * -5)(sqrt(15) * sqrt(18)) => 20(sqrt(15) * sqrt(18))#

Next, use this rule for multiplying radicals:

#sqrt(a) * sqrt(b) = sqrt(a * b)#

#20(sqrt(15) * sqrt(18)) => 20sqrt(15 * 18) => 20sqrt(270) =>#

#20sqrt(9 * 30) => 20(sqrt(9) * sqrt(30)) => (20 * 3)sqrt(30) =>#

#60sqrt(30)#