                </msub>
                    <mo>=</mo>
                    <mrow>
                        <mfenced open="(" close=")">
                            <mrow>
                                <msub><mi mathvariant="italic">x</mi>
                                <mi mathvariant="italic">nd</mi>
                                </msub>
                                <mo>+</mo>
                                <mn>1</mn>
                            </mrow>
                        </mfenced>
          