Solve the systems of equations using either elimination or substitution. System 1: (p+r)/5 = 2 (p-r)/4 = 2 System 2: (6-4)/b = 1 (9-8)/b = 1

Question image

Understand the Problem

The image shows a page from a math assignment dealing with systems of equations. It looks like the student is being asked to solve these systems using either elimination or substitution.

Answer

1) $p=9, r=1$ 2) $b=2$
Answer for screen readers
  1. $p = 9$, $r = 1$

  2. $b = 2$ (Assuming the first of the two equations for $b$ is the correct equation)

Steps to Solve

  1. Solve the first system of equations

The given equations are: $$ \frac{p+r}{5} = 2 $$ $$ \frac{p-r}{4} = 2 $$ First, we multiply both sides of each equation by the denominator to eliminate the fractions: $$ p + r = 10 $$ $$ p - r = 8 $$

  1. Eliminate $r$ by adding the two equations

Add the two equations together: $$ (p+r) + (p-r) = 10 + 8 $$ $$ 2p = 18 $$

  1. Solve for $p$

Divide both sides by 2: $$ p = \frac{18}{2} $$ $$ p = 9 $$

  1. Substitute the value of $p$ back into one of the equations to solve for $r$

Using the equation $p + r = 10$: $$ 9 + r = 10 $$ $$ r = 10 - 9 $$ $$ r = 1 $$

  1. Solve the second system of equations (which is actually a single variable equation)

The given equations are: $$ \frac{6-4}{b} = 1 $$ $$ \frac{9-8}{b} = 1 $$ Simplify each equation: $$ \frac{2}{b} = 1 $$ $$ \frac{1}{b} = 1 $$

  1. Solve for $b$ in each equation

From the first equation, multiply both sides by $b$: $$ 2 = b $$ So, $b = 2$

From the second equation, multiply both sides by $b$: $$ 1 = b $$ So, $b = 1$

  1. Check for consistency

Since we have two different values for $b$, $b=2$ and $b=1$, this system of equations is inconsistent and has no solution. There must be an error in the original problem statement, as systems of equations are expected to be consistent in math assignments. Assuming the first equation is correct, b=2.

  1. $p = 9$, $r = 1$

  2. $b = 2$ (Assuming the first of the two equations for $b$ is the correct equation)

More Information

Solving systems of equations allows us to find values for multiple variables that satisfy all equations simultaneously.

Tips

A common mistake is to make arithmetic errors when adding or subtracting equations. Another mistake can occur when substituting variables, forgetting to substitute in every instance of the variable. In the second system, the most common mistake would be to not recognize the inconsistency of the system.

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