Answer:
[tex]y\sqrt{2} + 3y\sqrt{2} = 4y\sqrt{2}[/tex]
Step-by-step explanation:
To add or subtract radicals, you need to simplify the radicals and then add the radicals
[tex]\sqrt{2y^2} + y\sqrt{18}[/tex]
First simplify [tex]\sqrt{2y^2}[/tex]
[tex]\sqrt{2y^2}[/tex]
[tex]\sqrt{2y^2} = \sqrt{2} \ \sqrt{y^2}[/tex]
[tex]\sqrt{2} \ \sqrt{y^2}[/tex]
[tex]\sqrt{y^2} = y[/tex]
[tex]\sqrt{2} \ y[/tex]
OR
[tex]y\sqrt{2} [/tex]
Second simplify [tex]\sqrt{18}[/tex]
To simplify [tex]y\sqrt{18}[/tex] you need to find two radicals that = [tex]\sqrt{18}[/tex] when you multiply them. One radical needs to be a perfect square and the other needs to be a non perfect square.
[tex]\sqrt{18}[/tex]
[tex]\sqrt{9} * \sqrt{2} = \sqrt{18}[/tex]
[tex]\sqrt{9} * \sqrt{2}}[/tex]
[tex]\sqrt{9} \sqrt{2}}[/tex]
[tex]3 \sqrt{2}}[/tex]
[tex]3 y\sqrt{2}}[/tex]
Now put it all together
[tex]y\sqrt{2} + 3y\sqrt{2} = 4y\sqrt{2}[/tex]