Find expert answers and community-driven knowledge on IDNLearn.com. Join our community to receive timely and reliable responses to your questions from knowledgeable professionals.

Select the best answer for the question.

Solve the system of equations [tex]2x + 3y = 40[/tex] and [tex]-2x + 2y = 20[/tex].

A. [tex]x = -6, y = 4[/tex]
B. [tex]x = -10, y = 20[/tex]
C. [tex]x = 2, y = 12[/tex]
D. [tex]x = 10, y = 20[/tex]


Sagot :

To solve the system of equations [tex]\(2x + 3y = 40\)[/tex] and [tex]\(-2x + 2y = 20\)[/tex], we'll use the substitution or elimination method. Here's the step-by-step process:

1. Write down the given equations:
[tex]\[ 2x + 3y = 40 \quad \text{(Equation 1)} \][/tex]
[tex]\[ -2x + 2y = 20 \quad \text{(Equation 2)} \][/tex]

2. Add the two equations together to eliminate [tex]\(x\)[/tex]:
[tex]\[ (2x + 3y) + (-2x + 2y) = 40 + 20 \][/tex]
Simplifying this, we get:
[tex]\[ 2x - 2x + 3y + 2y = 60 \][/tex]
[tex]\[ 0x + 5y = 60 \][/tex]
[tex]\[ 5y = 60 \][/tex]

3. Solve for [tex]\(y\)[/tex]:
[tex]\[ y = \frac{60}{5} \][/tex]
[tex]\[ y = 12 \][/tex]

4. Substitute [tex]\(y = 12\)[/tex] back into one of the original equations to solve for [tex]\(x\)[/tex]:
Using Equation 1:
[tex]\[ 2x + 3(12) = 40 \][/tex]
[tex]\[ 2x + 36 = 40 \][/tex]
[tex]\[ 2x = 40 - 36 \][/tex]
[tex]\[ 2x = 4 \][/tex]
[tex]\[ x = \frac{4}{2} \][/tex]
[tex]\[ x = 2 \][/tex]

5. Verifying the solution with the second equation:
Substituting [tex]\(x = 2\)[/tex] and [tex]\(y = 12\)[/tex] into Equation 2:
[tex]\[ -2(2) + 2(12) = 20 \][/tex]
[tex]\[ -4 + 24 = 20 \][/tex]
[tex]\[ 20 = 20 \quad \text{(True)} \][/tex]

Therefore, the solution to the system of equations is [tex]\(x = 2\)[/tex] and [tex]\(y = 12\)[/tex].

The best answer is:
C. [tex]\(x=2, y=12\)[/tex]