Bunuel
What is \(√1323+√588+√243\)?
A. 27√6
B. 54√6
C. 22√3
D. 44√3
E. 54√3
ALWAYS check the answer choices first.
The answer choices tell us that the 3 radicals (square root expressions) can probably all be rewritten as EITHER 3 times some integer OR 6 times some integer.
Since 1323 is ODD, we know that we can't rewrite it as 6 times some integer.
So, let's rewrite each expression as 3 time some integer.
√1323 + √588 + √243 = √(441 x 3) + √(196 x 3) + √(81 x 3)
Now we'll apply a nice rule that says: √(ab) = (√a)(√b)
= (√441)(√3) + (√196)(√3) + (√81)(√3)
√441 is a tough one to evaluate. However, if we recognize that √400 = 20, then perhaps √441 = 21. A quick check (21² = 441) confirms this.
√196 is a little easier. we might already know that √225 = 15, so we might check whether √196 = 14 A quick check (14² = 196) confirms this.
Finally, we should know that √81 = 9
So, we get....
= 21√3 + 14√3 + 9√3
= 44√3
Answer: D