Math Problem Statement

Two siblings, sibling A and sibling B, are saving money for their summer vacation. The amount of money that sibling A has in their savings account, y, can be represented by the equation y = 10x + 25, where x represents the number of weeks. Sibling B's savings can be represented by the equation y = 5x + 50. Based on the graph of this system of linear equations, after how many weeks will their savings accounts have the same amount of money?

Solution

Let's break down the two questions shown in the image.

Question 7: System of Linear Equations

  • Siblings' savings:
    • Sibling A's savings: y=10x+25y = 10x + 25
    • Sibling B's savings: y=5x+50y = 5x + 50

We are asked to determine when their savings will be the same (i.e., when the two equations intersect). To find this, set the equations equal to each other:

10x+25=5x+5010x + 25 = 5x + 50

Now, solve for xx:

10x5x=502510x - 5x = 50 - 25

5x=255x = 25

x=5x = 5

Thus, after 5 weeks, both siblings will have the same amount of money.

Correct answer: 5 weeks


Question 8: Rotation of Coordinates

The triangle has vertices at:

  • U(1,1)U(-1, 1)
  • V(0,4)V(0, -4)
  • W(4,1)W(-4, -1)

We need to rotate the triangle 90° counterclockwise and determine the new coordinates.

A 90° counterclockwise rotation rule is:

  • (x,y)(x, y) becomes (y,x)(-y, x)

Apply this rotation to each vertex:

  • U(1,1)U(-1, 1) becomes (1,1)(1,1)( -1, 1 ) \to (-1, -1)
  • V(0,4)V(0, -4) becomes (0,4)(4,0)( 0, -4 ) \to (4, 0)
  • W(4,1)W(-4, -1) becomes (4,1)(1,4)( -4, -1 ) \to (1, -4)

So the new coordinates are:

  • U(1,1)U'(-1, -1)
  • V(4,0)V'(4, 0)
  • W(1,4)W'(1, -4)

Correct answer: Option 2: U(1,1),V(4,0),W(1,4)U'(-1, -1), V'(4, 0), W'(1, -4)


Would you like more details on any of the steps? Let me know if you have any further questions!

Related Questions:

  1. How do you solve for the intersection point of two linear equations?
  2. What is the general method for performing a rotation of coordinates?
  3. How do different rotations (90°, 180°, 270°, etc.) affect coordinates?
  4. How do systems of equations help model real-life problems?
  5. What happens if the slope or y-intercept of one of the equations changes?

Tip: When solving systems of equations, always isolate the variable first (if possible), and check your solution by substituting it back into both original equations to ensure they are equal.

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Systems of Linear Equations
Solving for Intersection Points

Formulas

y = 10x + 25
y = 5x + 50

Theorems

Equating Linear Equations to Find Intersection

Suitable Grade Level

Grades 8-10