6. Find the zero of the polynomial: (4 marks)

(i) [tex]\( P(x) = x - 5 \)[/tex]

(ii) [tex]\( P(x) = 2x + 5 \)[/tex]

(iii) [tex]\( P(x) = 3 \)[/tex]

(iv) [tex]\( P(x) = cx + d \)[/tex], where [tex]\( c \neq 0 \)[/tex], and [tex]\( c \)[/tex] and [tex]\( d \)[/tex] are real numbers



Answer :

Let's solve each of the given polynomial equations step by step to find their zeros.

### (i) [tex]\(P(x) = x - 5\)[/tex]

To find the zero of the polynomial, we need to determine the value of [tex]\(x\)[/tex] that makes [tex]\(P(x)\)[/tex] equal to zero.

[tex]\[ P(x) = x - 5 \][/tex]

Setting [tex]\( P(x) = 0 \)[/tex]:

[tex]\[ x - 5 = 0 \][/tex]

Solving for [tex]\( x \)[/tex]:

[tex]\[ x = 5 \][/tex]

So, the zero of the polynomial [tex]\(P(x) = x - 5\)[/tex] is [tex]\( x = 5 \)[/tex].

### (ii) [tex]\(P(x) = 2x + 5\)[/tex]

Similarly, we need to find the value of [tex]\(x\)[/tex] that makes [tex]\(P(x)\)[/tex] equal to zero.

[tex]\[ P(x) = 2x + 5 \][/tex]

Setting [tex]\( P(x) = 0 \)[/tex]:

[tex]\[ 2x + 5 = 0 \][/tex]

Solving for [tex]\( x \)[/tex]:

[tex]\[ 2x = -5 \][/tex]

[tex]\[ x = -\frac{5}{2} \][/tex]

So, the zero of the polynomial [tex]\(P(x) = 2x + 5\)[/tex] is [tex]\( x = -\frac{5}{2} \)[/tex].

### (iii) [tex]\(P(x) = 3\)[/tex]

Here, we need to find the value of [tex]\(x\)[/tex] that makes [tex]\(P(x)\)[/tex] equal to zero.

[tex]\[ P(x) = 3 \][/tex]

Setting [tex]\( P(x) = 0 \)[/tex]:

[tex]\[ 3 = 0 \][/tex]

This is a contradiction because 3 can never equal 0. Therefore, there are no values of [tex]\(x\)[/tex] that satisfy this equation.

So, the polynomial [tex]\(P(x) = 3\)[/tex] has no zeros.

### (iv) [tex]\(P(x) = cx + d\)[/tex], [tex]\(c \neq 0\)[/tex]

To find the zero, we set the polynomial equal to zero and solve for [tex]\(x\)[/tex]:

[tex]\[ P(x) = cx + d \][/tex]

Setting [tex]\( P(x) = 0 \)[/tex]:

[tex]\[ cx + d = 0 \][/tex]

Solving for [tex]\( x \)[/tex]:

[tex]\[ cx = -d \][/tex]

[tex]\[ x = -\frac{d}{c} \][/tex]

So, the zero of the polynomial [tex]\(P(x) = cx + d\)[/tex] with [tex]\(c \neq 0\)[/tex] is [tex]\( x = -\frac{d}{c} \)[/tex].

### Summary:

- The zero of [tex]\(P(x) = x - 5\)[/tex] is [tex]\( x = 5 \)[/tex].
- The zero of [tex]\(P(x) = 2x + 5\)[/tex] is [tex]\( x = -\frac{5}{2} \)[/tex].
- The polynomial [tex]\(P(x) = 3\)[/tex] has no zeros.
- The zero of [tex]\(P(x) = cx + d\)[/tex] with [tex]\(c \neq 0\)[/tex] is [tex]\( x = -\frac{d}{c} \)[/tex].