Question

The direction ratio of the normal to the plane 7x + 4y - 2z + 5 = 0 are-

1. 7, 4, -2
2. 7, 4, 5
3. 7, 4, 2
4. 4, -2, 5

Answer: 7, 4, -2

Solution :-

We know that the Cartesian equation of the plane is $ax+by+cz=d$ , where a, b and c are direction ratios of the normal to the plane.

Now, compare $7x+4y-2z+5=0$ with Cartesian equation of the plane then we get direction ratios of this equation a = 7, b = 4 and c = -2.

So, the direction ratio of the normal to the plane $7x+4y-2z+5=0$ are- 7, 4, -2.

So, correct answer is option-1, $\to 7,4,-2$