the sum of radical-18 and radical-72 is?

Question

√-18 + √-72  ?

Answer 1

The rules are √(ab) = √a√b and √-1 = i (symbol for the imaginary number √-1)

 

√-18 + √-72 = √-9√2 + √-36√2 = (3√2)i + (6√2)i = (9√2)i

Answer 2

Mariah,

 

We can factor √-18 + √-72 as √-(9·2) + √–(9·4·2) = 3√(-2) + 6·√(-2) = 9·√(-2)

 

And since √(-1) = i

 

We now have: 

 

√-18 + √-72 = 9i·√2

Answer 3

√-18=√(9)(2)(-1)=√9√2√-1=3i√2   (√-1=i, the imaginary number)

√-72=√(36)(2)(-1)=√36√2√-1=6i√2

3i√2+6i√2=9i√2