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Question

If x = 3 so, what is the value of x 2 + 2x + 5 ?

The correct answer is

20

Evaluating the Expression

We are given an algebraic expression and a specific value for the variable \(x\). Our task is to substitute this value into the expression and calculate the result.

The given expression is:

\(x^2 + 2x + 5\)

The given value for \(x\) is:

\(x = 3\)

Steps to Evaluate the Expression

To find the value of the expression when \(x = 3\), we substitute 3 for every instance of \(x\) in the expression.

  1. Substitute \(x=3\) into the expression \(x^2 + 2x + 5\).
  2. Calculate each term separately.
  3. Add the results together.

Let's substitute \(x = 3\) into the expression:

\((3)^2 + 2(3) + 5\)

Now, we calculate each part:

  • First term: \(x^2\) becomes \((3)^2\). The square of 3 is \(3 \times 3\).
  • \((3)^2 = 9\)
  • Second term: \(2x\) becomes \(2(3)\). Multiply 2 by 3.
  • \(2(3) = 6\)
  • Third term: The constant term is 5.

Now, we add the values of the terms together:

\(9 + 6 + 5\)

Performing the addition:

\(9 + 6 = 15\)

\(15 + 5 = 20\)

So, the value of the expression \(x^2 + 2x + 5\) when \(x = 3\) is 20.

Checking the Options

Let's compare our result with the given options:

Option Value Matches our result?
1 15 No
2 20 Yes
3 25 No
4 35 No

Our calculated value, 20, matches Option 2.

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Important Questions from Polynomials

  1. If y 2= y + 7, then what is the value of y 3?

  2. Factorize x 2- y 2- 9z 2+ 6yz

  3. If one of the zeros of the polynomial x 3+ ax 2+ bx + c is  - 1, then the product of other two zeros is equal to :

  4. Which of the following is a trinomial?

  5. If a(a + b + c) 2 = 1792; b(a + b + c) 2 = 1536; c(a + b + c) 2 = 768, then what will be the value of b?

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