Question

21. Find the value of the polynomial 5x2 – 3x + 2 at i) x=2 ii) x=-1.​

Answer 1

Given:

• 5x²– 3x +2
• value of x = 2
• value of x = -1

To find:

• value of polynomial on both given value of x

Solution:

We are given polynomial is 5x²– 3x +2.

Find value of polynomial on value of x = 2

P(x) = 5x²– 3x +2

[Where x = 2]

→ P(2) = 5×2²– 3×2 + 2

→ P(2) = 5×4 – 6 + 2

→ P(2) = 20 – 4

→ P(2) = 16

Therefore,

Value of given polynomial on the value of x = 2 is 16

Finding value of polynomial on value of x = –1

P(x) = 5x² – 3x +2

[Where x = –1]

→ P(-1) = 5×(-1)² -3×(-1) +2

→ P(-1) = 5 +3 + 2

→ P(-1) = 10

Therefore,

Value of given polynomial on the given value of x = (-1) is 10

Answer 2

Answer: This is when x=2.

Step-by-step explanation:

The value of 5x  

2

–3x+2 when x=2 is calculated as below,

5x  

2

–3x+2=5∗(2)  

2

–3∗(2)+2

On simplification, we get

=5∗4–3∗2+2

=20–6+2

=22–6

=16.

Hence, the value of 5x p(x)=5x  

2

−3x+7

Thus,

p(1)=5(1)  

2

−3(1)+7

p(1)=5−3+7=9

2

–3x+2=5 when x=2 is 16.