Question

Help please, not sure how to do this....

Answer 1

`4√(2b)`

Explanation:

`√(98b)-√(72b)+√(18b)`

Apply radical rule
`√(ab) =√(a) √(b)`:

`\implies √(98)√(b) -√(72)√(b) +√(18)√(b)`

Factor out common term
`√(b)`:

`\implies √(b)(√(98) -√(72)+√(18))`

Rewrite 98, 72 and 18:

`\implies √(b)(√(49 \cdot 2) -√(36 \cdot 2)+√(9 \cdot 2))`

`\implies √(b)(√(49)√(2) -√(36)√(2)+√(9)√(2))`

`\implies √(b)(7√(2) -6√(2)+3√(2))`

Factor out common term
`√(2)`:

`\implies √(b)√(2)(7 -6+3)`

`\implies √(b)√(2)(4)`

`\implies 4√(2b)`