Show how to evaluate the equation for x=2 and x=5 without simplifying first plug in the x values

1 answer

To evaluate an expression for specific values of \( x \) without simplifying first, you can substitute the values directly into the expression.

Let's say we have an arbitrary equation (for demonstration), such as:

\[ y = 3x^2 + 4x - 5 \]

Evaluating for \( x = 2 \):

  1. Substitute \( x = 2 \) into the equation:

\[ y = 3(2)^2 + 4(2) - 5 \]

This means we directly plug in \( 2 \) for \( x \).

Evaluating for \( x = 5 \):

  1. Substitute \( x = 5 \) into the equation:

\[ y = 3(5)^2 + 4(5) - 5 \]

Now we'll compute the result for both values but we'll follow through without simplifying the whole expression at once.

Final calculations:

For \( x = 2 \):

\[ y = 3(2)^2 + 4(2) - 5 \ = 3(4) + 4(2) - 5 \ = 12 + 8 - 5 \ = 20 - 5 \ = 15 \]

Thus, when \( x = 2 \), \( y = 15 \).

For \( x = 5 \):

\[ y = 3(5)^2 + 4(5) - 5 \ = 3(25) + 4(5) - 5 \ = 75 + 20 - 5 \ = 95 - 5 \ = 90 \]

Thus, when \( x = 5 \), \( y = 90 \).

Summary of Results:

  • For \( x = 2 \), \( y = 15 \)
  • For \( x = 5 \), \( y = 90 \)

This method allows you to see the steps of evaluation without first simplifying the whole equation into a single numeric expression.