Simplify square root of 98x^4y^2-3x^2y square root of 2

$\sqrt{98 x^{4} y^{2}} - 3 x^{2} y \sqrt{2}$

Simplify each term.

Rewrite $98 x^{4} y^{2}$ as ${(7 x^{2} y)}^{2} \cdot 2$ .

Factor $49$ out of $98$ .

$\sqrt{49 (2) x^{4} y^{2}} - 3 x^{2} y \sqrt{2}$

Rewrite $49$ as $7^{2}$ .

$\sqrt{7^{2} \cdot 2 x^{4} y^{2}} - 3 x^{2} y \sqrt{2}$

Rewrite $x^{4}$ as ${(x^{2})}^{2}$ .

$\sqrt{7^{2} \cdot 2 {(x^{2})}^{2} y^{2}} - 3 x^{2} y \sqrt{2}$

Move $2$ .

$\sqrt{7^{2} {(x^{2})}^{2} y^{2} \cdot 2} - 3 x^{2} y \sqrt{2}$

Rewrite $7^{2} {(x^{2})}^{2} y^{2}$ as ${(7 x^{2} y)}^{2}$ .

$\sqrt{{(7 x^{2} y)}^{2} \cdot 2} - 3 x^{2} y \sqrt{2}$

Pull terms out from under the radical.

$7 x^{2} y \sqrt{2} - 3 x^{2} y \sqrt{2}$

Subtract $3 x^{2} y \sqrt{2}$ from $7 x^{2} y \sqrt{2}$ .

$4 x^{2} y \sqrt{2}$