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If ∣x84x∣=∣62186∣\left|\begin{matrix} x & 8 \\ 4 & x \end{matrix}\right| = \left|\begin{matrix} 6 & 2 \\ 18 & 6 \end{matrix}\right|, then xx is/are equal to

Solution

✅ Correct Option: 1

For a 2×2 matrix ∣abcd∣\left|\begin{matrix} a & b \\ c & d \end{matrix}\right|, the determinant is:

ad−bcad - bc


Calculate the left side determinant:

∣x84x∣\left|\begin{matrix} x & 8 \\ 4 & x \end{matrix}\right|

=x×x−8×4= x \times x - 8 \times 4

=x2−32= x^2 - 32


Calculate the right side determinant:

∣62186∣\left|\begin{matrix} 6 & 2 \\ 18 & 6 \end{matrix}\right|

=6×6−2×18= 6 \times 6 - 2 \times 18

=36−36= 36 - 36

=0= 0


Since the determinants are equal:

x2−32=0x^2 - 32 = 0

x2=32x^2 = 32

x=±32x = \pm\sqrt{32}


Simplify 32\sqrt{32}:

32=16×2\sqrt{32} = \sqrt{16 \times 2}

=16×2= \sqrt{16} \times \sqrt{2}

=42= 4\sqrt{2}

Therefore, x=±42x = \pm 4\sqrt{2}

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