mml=<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><msup><mfenced separators="|"><mrow><mi mathvariant="normal">m</mi><mo>+</mo><mi mathvariant="normal">n</mi></mrow></mfenced><mn>2</mn></msup><mrow><msup><mi mathvariant="normal">m</mi><mn>2</mn></msup><mo>-</mo><msup><mi mathvariant="normal">n</mi><mn>2</mn></msup></mrow></mfrac><mo>=</mo><mfrac><mrow><mfenced separators="|"><mrow><mi mathvariant="normal">m</mi><mo>+</mo><mi mathvariant="normal">n</mi></mrow></mfenced><mfenced separators="|"><mrow><mi mathvariant="normal">m</mi><mo>+</mo><mi mathvariant="normal">n</mi></mrow></mfenced></mrow><mrow><mfenced separators="|"><mrow><mi mathvariant="normal">m</mi><mo>+</mo><mi mathvariant="normal">n</mi></mrow></mfenced><mfenced separators="|"><mrow><mi mathvariant="normal">m</mi><mo>-</mo><mi mathvariant="normal">n</mi></mrow></mfenced></mrow></mfrac><mo>=</mo><mfrac><mrow><mi mathvariant="normal">m</mi><mo>+</mo><mi mathvariant="normal">n</mi></mrow><mrow><mi mathvariant="normal">m</mi><mo>-</mo><mi mathvariant="normal">n</mi></mrow></mfrac></math>