Questions: Consider the following 3 expressions. To be the same, what would P, Q, and R have to be?
P x^2 + 6 x + 1 x^2 + x(x + Q) + 1 3 x^2 - 5 - (x^2 - 6 x + R/2)
P= Q= R=
Transcript text: Consider the following 3 expressions. To be the same, what would $P, Q$, and $R$ have to be?
\[
\begin{array}{lll}
P x^{2}+6 x+1 & x^{2}+x(x+Q)+1 & 3 x^{2}-5-\left(x^{2}-6 x+\frac{R}{2}\right) \\
P= & Q= & R=
\end{array}
\]
Solution
Solution Steps
To determine the values of \( P \), \( Q \), and \( R \) that make the given expressions equivalent, we need to equate the coefficients of the corresponding terms in each expression. This involves expanding and simplifying the expressions and then comparing the coefficients of \( x^2 \), \( x \), and the constant terms.
Step 1: Equate the First Expression
We start with the first expression:
\[ P x^2 + 6x + 1 \]
Step 2: Equate the Second Expression
Next, we look at the second expression:
\[ x^2 + x(x + Q) + 1 \]
Simplify the second expression:
\[ x^2 + x^2 + Qx + 1 \]
\[ 2x^2 + Qx + 1 \]
Step 3: Equate the Third Expression
Now, consider the third expression:
\[ 3x^2 - 5 - \left(x^2 - 6x + \frac{R}{2}\right) \]
Simplify the third expression:
\[ 3x^2 - 5 - x^2 + 6x - \frac{R}{2} \]
\[ 2x^2 + 6x - 5 - \frac{R}{2} \]
Step 4: Compare the Expressions
We need to compare the simplified forms of the three expressions to find \( P \), \( Q \), and \( R \).
From the first and second expressions:
\[ P x^2 + 6x + 1 = 2x^2 + Qx + 1 \]
By comparing coefficients:
\[ P = 2 \]
\[ 6 = Q \]
From the first and third expressions:
\[ P x^2 + 6x + 1 = 2x^2 + 6x - 5 - \frac{R}{2} \]
By comparing coefficients:
\[ P = 2 \]
\[ 1 = -5 - \frac{R}{2} \]
Solve for \( R \):
\[ 1 + 5 = -\frac{R}{2} \]
\[ 6 = -\frac{R}{2} \]
\[ R = -12 \]