MCQ
A quadratic equation whose one root is 3 is
- A$x^2-5 x+6=0$
- B$x^2-6 x-6=0$
- C$x^2-5 x-6=0$
- ✓
✓
Answer
Correct option: D.
(D) $x^2-5 x+6=0$
Explanation: since 3 is the root of the equation, x = 3 must satisfy the equation.
Applying x = 3 in the equation $x^2-5 x+6=0$
gives, $(3)^2-5(3)+6=0$
$\Rightarrow 9-15+6=0$
$\Rightarrow 15-15=0$
$\Rightarrow 0=0$
$\Rightarrow$ L.H.S. = R.H.S.
Hence, $x^2-5 x+6=0$ is a required equation which has 3 as root.
Explanation: since 3 is the root of the equation, x = 3 must satisfy the equation.
Applying x = 3 in the equation $x^2-5 x+6=0$
gives, $(3)^2-5(3)+6=0$
$\Rightarrow 9-15+6=0$
$\Rightarrow 15-15=0$
$\Rightarrow 0=0$
$\Rightarrow$ L.H.S. = R.H.S.
Hence, $x^2-5 x+6=0$ is a required equation which has 3 as root.
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