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(Will l give 25 points!) Solve the system of linear equations by substitution. -8x + y = 5 and 5x - y = 3

Sagot :

Answer:

x = -8/3 and y = -49/3

Step-by-step explanation:

(Step 1) To solve using substitution, you first need to isolate a variable in one of these equations. I chose to isolate "y" in the following equation.

-8x + y = 5                                        <--- Original equation

y = 5 + 8x                                         <--- Add 8x to both sides

(Step 2) Now, substitute (5 + 8x) for "y" in the second equation.

5x - y = 3                                          <--- Original equation

5x - (5 + 8x) = 3                               <--- Substitute 5 + 8x for "y"

5x - 5 - 8x = 3                                  <--- Distribute (-) in the parentheses

-3x - 5 = 3                                        <--- Combine terms with "x"

-3x = 8                                              <--- Add 5 to both sides

x = -8/3                                             <--- Divide both sides by -3

(Step 3) Since you know the value of "x", plug it into one of the equations to solve for "y".

y = 5 + 8x                                         <--- Original (rearranged) equation

y = 5 + 8(-8/3)                                   <--- Plug (-8/3) for "x"

y = 5 - 64/3                                       <--- Multiply

y = 15/3 - 64/3                                   <--- Convert 5 into a fraction

y = -49/3                                           <--- Subtract

(Step 3.5) You can check your work by plugging "y" into the other equation to see if the answer for "x" is the same.

5x - y = 3                                             <--- Original equation

5(-8/3) - y = 3                                      <--- Plug (-8/3) for "x"

-40/3 - y = 3                                        <--- Multiply

-40/3 - y = 9/3                                     <--- Convert 3 into a fraction

-49/3 - y = 0                                        <--- Subtract both sides by 9/3

-49/3 = y                                             <--- Add both sides by "y"

The value of the system of equations is x = -8/3 and y = -49/3.

this question is hard what the heck