Math Problem Statement

Tyler and Han are trying to solve this system by substitution: x + 3y = -5 and 9x + 3y = 3. Tyler's first step is to isolate x in the first equation to get x = -5 - 3y. Han's first step is to isolate 3y in the first equation to get 3y = -5 - x. Show that both first steps can be used to solve the system and will yield the same solution.

Solution

Let's solve the given problem step by step and show that both methods result in the same solution.


The system of equations is:

  1. x+3y=5x + 3y = -5
  2. 9x+3y=39x + 3y = 3

Tyler's First Step: Isolate xx in the first equation.

Starting with x+3y=5x + 3y = -5: x=53yx = -5 - 3y

Substitute x=53yx = -5 - 3y into the second equation 9x+3y=39x + 3y = 3: 9(53y)+3y=39(-5 - 3y) + 3y = 3

Simplify: 4527y+3y=3-45 - 27y + 3y = 3 4524y=3-45 - 24y = 3 24y=48(add 45 to both sides)-24y = 48 \quad \text{(add 45 to both sides)} y=2y = -2

Now substitute y=2y = -2 back into x=53yx = -5 - 3y: x=53(2)x = -5 - 3(-2) x=5+6x = -5 + 6 x=1x = 1

Thus, the solution is: (x,y)=(1,2)(x, y) = (1, -2)


Han's First Step: Isolate 3y3y in the first equation.

Starting with x+3y=5x + 3y = -5: 3y=5x3y = -5 - x

Substitute 3y=5x3y = -5 - x into the second equation 9x+3y=39x + 3y = 3: 9x+(5x)=39x + (-5 - x) = 3

Simplify: 9x5x=39x - 5 - x = 3 8x5=38x - 5 = 3 8x=8(add 5 to both sides)8x = 8 \quad \text{(add 5 to both sides)} x=1x = 1

Now substitute x=1x = 1 back into 3y=5x3y = -5 - x: 3y=513y = -5 - 1 3y=63y = -6 y=2y = -2

Thus, the solution is: (x,y)=(1,2)(x, y) = (1, -2)


Conclusion:

Both Tyler's and Han's approaches lead to the same solution, (x,y)=(1,2)(x, y) = (1, -2).

Would you like a breakdown of any specific step? Let me know!


Related Questions:

  1. Can you explain the substitution method in general?
  2. How does isolating xx versus isolating 3y3y affect the solution process?
  3. Can this system also be solved using the elimination method?
  4. How can graphing the equations confirm the solution?
  5. What are some common mistakes to avoid when using substitution?

Tip:

Always double-check your substitution by plugging the solution back into both original equations to ensure it satisfies both!

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Equations
Substitution Method

Formulas

Substitution method formulas for solving linear systems

Theorems

Properties of equality in solving equations

Suitable Grade Level

Grades 8-10