Math  /  Algebra

QuestionLet x represent one number and let y represent the other number. Four times a first number decreased by a second number is -13 . The first number increased by twice the second number is 17 . Use the given conditions to write a system of equations. Solve the system and find the numbers.

Studdy Solution

STEP 1

1. Let x x represent the first number.
2. Let y y represent the second number.
3. Four times the first number decreased by the second number is -13.
4. The first number increased by twice the second number is 17.
5. We need to write a system of equations based on these conditions and solve for x x and y y .

STEP 2

1. Translate the word problem into mathematical equations.
2. Write the system of equations.
3. Solve the system of equations using substitution or elimination.
4. Find the values of x x and y y .

STEP 3

Translate the word problem into mathematical equations.
For the first condition: "Four times a first number decreased by a second number is -13", we write: 4xy=13 4x - y = -13
For the second condition: "The first number increased by twice the second number is 17", we write: x+2y=17 x + 2y = 17

STEP 4

Write the system of equations.
The system of equations is: \begin{align*} 1) & \quad 4x - y = -13 \\ 2) & \quad x + 2y = 17 \end{align*}

STEP 5

Solve the system of equations using substitution or elimination. Here, we will use the elimination method.
First, multiply equation (2) by 2 to align the coefficients of y y : 2(x+2y)=2(17)2(x + 2y) = 2(17) 2x+4y=342x + 4y = 34
Now, we have: \begin{align*} 1) & \quad 4x - y = -13 \\ 3) & \quad 2x + 4y = 34 \end{align*}

STEP 6

Continue solving by eliminating x x .
Multiply equation (1) by 2 to align the coefficients of x x : 2(4xy)=2(13)2(4x - y) = 2(-13) 8x2y=268x - 2y = -26
Now, subtract equation (3) from the new equation: \begin{align*} 8x - 2y &= -26 \\ -(2x + 4y &= 34) \end{align*}
This gives: 6x6y=606x - 6y = -60
Divide the entire equation by 6: xy=10x - y = -10

STEP 7

Substitute x=y10 x = y - 10 into equation (2) to solve for y y .
Substitute into equation (2): (y10)+2y=17(y - 10) + 2y = 17 y10+2y=17y - 10 + 2y = 17 3y10=173y - 10 = 17
Add 10 to both sides: 3y=273y = 27
Divide by 3: y=9y = 9

STEP 8

Now substitute y=9 y = 9 back into the expression for x x .
Substitute into x=y10 x = y - 10 : x=910x = 9 - 10 x=1x = -1
The numbers are: x=1 x = -1 and y=9 y = 9

Was this helpful?

Studdy solves anything!

banner

Start learning now

Download Studdy AI Tutor now. Learn with ease and get all help you need to be successful at school.

ParentsInfluencer programContactPolicyTerms
TwitterInstagramFacebookTikTokDiscord