Question

If one zero of the quadratic polynomial x2 + 3x + b is 2, then the value of b is (a) 10
(b) -8 (c) 9 (d) -10

Answer 1

Answer:

The correct answer is option (d) -10

Step-by-step explanation:

Given,

One zero of the polynomial x² +3x+b is 2

To find,

The value of 'b'

Recall the concept:

If 'a' is a zero of the polynomial p(x), then p(a) = 0

Solution:

Let the given polynomial be p(x),

Since 2 is a zero of the polynomial p(x), then we have p(2) = 0

We have p(x) = x² +3x+b

Substituting the value of x = 2 we get,

p(2) = 2² +3×2+b

= 4+6+ b

= 10 +b

p(2) = 0⇒ 10+b = 0

b = -10

The value of b = -10

The correct answer is option (d) -10

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