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Solve each system of equations using elimination.

[tex]\[
\begin{array}{l}
9p + 8q = 2 \\
6p - 5q = 26
\end{array}
\][/tex]

A. [tex]\( p = -0.67, \, q = 2.65 \)[/tex]
B. [tex]\( p = 2.34, \, q = -7.4 \)[/tex]
C. [tex]\( p = 2.34, \, q = -2.39 \)[/tex]
D. [tex]\( p = -1.9, \, q = -2.39 \)[/tex]


Sagot :

Sure, let's solve the system of equations using the elimination method step by step:

Given the system of equations:

1. [tex]\(9p + 8q = 2\)[/tex]
2. [tex]\(6p - 5q = 26\)[/tex]

Step 1: Align the coefficients for elimination
- We need to eliminate one of the variables, so let's align the coefficients of [tex]\(p\)[/tex].

To do this, we can multiply the first equation by 6 and the second equation by 9, in order to make the coefficients of [tex]\(p\)[/tex] the same (54):

- First equation: [tex]\(6 \times (9p + 8q) = 6 \times 2 \)[/tex]
- Second equation: [tex]\(9 \times (6p - 5q) = 9 \times 26\)[/tex]

This gives us the new system:
[tex]\[ 54p + 48q = 12 \quad \text{(Equation 3)} \][/tex]
[tex]\[ 54p - 45q = 234 \quad \text{(Equation 4)} \][/tex]

Step 2: Subtract the second equation from the first

Now, subtract Equation 4 from Equation 3 to eliminate [tex]\(p\)[/tex]:

[tex]\[ (54p + 48q) - (54p - 45q) = 12 - 234 \][/tex]

This simplifies to:

[tex]\[ 0p + 93q = -222 \][/tex]

or simply:

[tex]\[ 93q = -222 \][/tex]

Step 3: Solve for [tex]\(q\)[/tex]

Divide both sides by 93:

[tex]\[ q = \frac{-222}{93} \approx -2.39 \][/tex]

Step 4: Substitute [tex]\(q\)[/tex] back into one of the original equations to solve for [tex]\(p\)[/tex]

Let's use the first equation:

[tex]\[ 9p + 8q = 2 \][/tex]

Substitute [tex]\(q = -2.39\)[/tex]:

[tex]\[ 9p + 8(-2.39) = 2 \][/tex]

Simplify:

[tex]\[ 9p - 19.12 = 2 \][/tex]

Add 19.12 to both sides:

[tex]\[ 9p = 21.12 \][/tex]

Divide by 9:

[tex]\[ p = \frac{21.12}{9} \approx 2.34 \][/tex]

So, the solution to the system of equations is:

[tex]\[ p \approx 2.34, \quad q \approx -2.39 \][/tex]

Step 5: Validate the given options with our solution:

a. [tex]\(p = -0.67, q = 2.65\)[/tex] – Wrong
b. [tex]\(p = 2.34, q = -74\)[/tex] – Wrong
c. [tex]\(p = 2.34, q = -2.39\)[/tex] – Correct!
d. [tex]\(p = -1.9, q = -2.39\)[/tex] – Wrong

Thus, the correct solution is option c:
[tex]\[ p = 2.34, q = -2.39 \][/tex]