Question

Find the value of the polynomial 5x +4x2 – 3 at x = - 1 and x = 2​

Answer 1

Answer:

x= -1

5(-1)+4(-1)²-3

-5+4-3

-1-3

= -4

x=2

5(2)+4(2)²-3

10+16-3

26-3

23

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Answer 2

• The value of the polynomial when x = –1 = –4.
• The value of the polynomial when x = 2 = 23.

Given :–

• A polynomial = 5x + 4x² – 3.
• x = –1.
• x = 2.

To Find :–

• The value of the given polynomial at x = –1 and x = 2.

Solution :–

• x = –1.

Given polynomial,

→ 5x + 4x² – 3

Now, substitute the value of x in the given polynomial.

→ 5(–1) + 4(–1)² – 3

We know that,

• Negative × Negative = Positive.

So,

→ (–1)² = (–1) × (–1) = 1

→ 5 × (–1) + 4 × 1 – 3

→ –5 + 4 –3

→ –5 – 3 + 4

→ –8 + 4

→ –4

Hence,

The value of the given polynomial at x = –1 is –4.

• 2) x = 2.

Given polynomial,

→ 5x + 4x² – 3

Now, substitute the value of x in the given polynomial.

→ 5(2) + 4(2)² – 3

We know that,

• (2)² = 2 × 2 = 4.

→ 5 × 2 + 4 × 4 – 3

→ 10 + 16 – 3

→ 26 – 3

→ 23

Hence,

The value of the given polynomial at x = 2 is 23.