If x,y,z are in GP,then using properties of determinants,show that Δ=∣∣
∣∣px+yxypy+zyz0px+ypy+z∣∣
∣∣=0,where x≠y≠z and p is any real number.
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Solution
Let Δ=∣∣
∣∣px+yxypy+zyz0px+ypy+z∣∣
∣∣ By C1→C1−pC1−C3,Δ=∣∣
∣
∣∣0xy0yz−p2x−py−py−zpx+ypy+z∣∣
∣
∣∣ Expanding along C1,Δ=(−p2x−2py−z)(xz−y2) ∵ x,y,z are in GP,so xz=y2⇒xz−y2=0∴Δ=0