MCQ
Which of the following equations has 2 as a root?
- A$x^2-4 x+5=0$
- B$x^2+3 x-12=0$
- ✓$2 x^2-7 x+6=0$
- D$3 x^2-6 x-2=0$
✓
Answer
Correct option: C.
$2 x^2-7 x+6=0$
$2 x^2-4 x+5=0$
$\Rightarrow(2)^2-4 x^2+5=0$
$\Rightarrow 4-8+5=0$
$\Rightarrow 9-8 \neq 0$
2 is not its root.
$x 2+3 x-12=0$
$\Rightarrow(2)^2-3 \times 2-12=0$
$\Rightarrow 4-6-12$
$=4-18$
$=-14$
$\therefore 2$ is not its roots.
$2 x^2-7 x+6=0$
$\Rightarrow 2(2)^2-7 \times 2+6=0$
$\Rightarrow 8-14+6=0$
$\Rightarrow 0=0$
$\therefore 2$ is its roots.
$3 x^2-6 x-2=0$
$\Rightarrow 3(2)^2-6 \times 2-2=0$
$\Rightarrow 12-12-2=0$
$\Rightarrow 12-14=0$
$\therefore 2$ is not its roots.
$\Rightarrow(2)^2-4 x^2+5=0$
$\Rightarrow 4-8+5=0$
$\Rightarrow 9-8 \neq 0$
2 is not its root.
$x 2+3 x-12=0$
$\Rightarrow(2)^2-3 \times 2-12=0$
$\Rightarrow 4-6-12$
$=4-18$
$=-14$
$\therefore 2$ is not its roots.
$2 x^2-7 x+6=0$
$\Rightarrow 2(2)^2-7 \times 2+6=0$
$\Rightarrow 8-14+6=0$
$\Rightarrow 0=0$
$\therefore 2$ is its roots.
$3 x^2-6 x-2=0$
$\Rightarrow 3(2)^2-6 \times 2-2=0$
$\Rightarrow 12-12-2=0$
$\Rightarrow 12-14=0$
$\therefore 2$ is not its roots.
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