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If x = 1 is a common root of the equations ax2 + ax + 3 = 0 and x2 + x + b = 0, then the value of ab is : A) 3B) 6 C) 3.5 D) -3 |
Answer» Correct option is (A) 3 Given that x = 1 is a root of equation \(ax^2+ax+3=0\) \(\therefore a.1^2+a.1+3=0\) \(\Rightarrow\) a+a+3 = 0 \(\Rightarrow\) 2a = -3 \(\Rightarrow a=\frac{-3}2\) Also given that x = 1 is a root of equation \(x^2+x+b=0.\) \(\therefore1^2+1+b=0\) \(\Rightarrow b=-2\) Now, ab \(=\frac{-3}2\times-2=3\) Correct option is A) 3 |
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