How do you multiply #sqrt81*sqrt36#?

Question

2184 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-07-03T13:05:01

#+-54#

Given: #sqrt81*sqrt36#

Use the fact that #sqrta*sqrtb=sqrt(ab) \ AAa,b>=0#.

#=sqrt(81*36)#

#=sqrt(2916)#

#=sqrt(54^2)#

Now, use the fact that #sqrt(a^2)=+-a#.

#=+-54#

Answer 2 · 2018-07-03T19:41:35

#sqrt(81) * sqrt(36) = +-54#

It can be done either of 2 ways: take square root first, then multiply
or multiply first, then take square root.

#sqrt(81) * sqrt(36) = +-9 * +-6 = +-54#

#sqrt(81) * sqrt(36) = sqrt(81*36) = sqrt(2916) = +-54#

I hope this helps,
Steve