# If the value of determinant |[m,2],[-5,7]| is 31, find the value of m - Algebra

If the value of determinant |[m,2],[-5,7]|is 31, find the value of m

#### Solution

|[m,2],[-5,7]|=31

∴(m × 7) – (–5 × 2) = 31
∴7m – (–10) = 31
∴7m + 10 = 31
∴7m = 21
∴m = 3

Concept: Determinant of Order Two
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