Question bank/JEE Main/Mathematics

JEE MainMathematicsModerateQuadratic Equations

If 2x2+3x+4=02x^{2} + 3x + 4 = 0 and ax2+bx+c=0ax^{2} + bx + c = 0 where
a,b,c∈Na,b,c \in N have a common root, then the least value of a + b + c is

Show answer and solution
2x2+3x+4=02x^{2} + 3x + 4 = 0 has imaginary roots. Thus the given
equations have identical roots.

∴a2=b3=c4=k(say)\therefore\frac{a}{2} = \frac{b}{3} = \frac{c}{4} = k(say)
⇒a+b+c=9k\Rightarrow a + b + c = 9k for least value take k = 1

Source: Grass-G / M-16 Mathematics Paper 25 Nov First.docx

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