Question

1) Choose correct option: [1]
If one zero of quadratic polynomial 3x2 + k is 2, find its other zero.
(a) 1 (b) - 2 (c) 3 (d) - 3
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Answer 1

Answer:

option a is correct for this question

Answer 2

Answer:

b. -2

Step-by-step explanation:

Zero of a polynomial means that by putting that number in place of the variable, the polynomial will become zero.

For example, consider the following polynomial:

p(x) = x + 3

Now , if we put x = -3, the polynomial will become zero; therefore, '-3' is a zero of this polynomial.

Now as we are given a polynomial;

p(x) = 3x² + k

Along with its one zero, which is '2', now by definition of zero, by putting this 2 into the polynomial, should give a zero;

Then;

3(2)²+k = 0

Now we can compute 'k';

k = -12

Now putting that 'k' into the given polynomial;

p(x) = 3x²-12

Now for the other zero;

We simply put the given answer one-by-one to find for what value the polynomial gives a zero;

You can try for all, but for x=-2;

p(-2) = 3(-2)²-12

And, solving it as;

p(-2) = 3(4)-12

p(-2)=12-12=0

Hence, the other zero is '-2'.