Mathematics
myamorales01
24

Ernesto tried to determine the solution for the system of equations using substitution. His work is shown below. x _ y = 7 3x _ 2y = 8 Step 1: x = y + 7 Step 2: 3(y + 7) _ 2y = 8 Step 3: 3y + 7 _ 2y = 8 Step 4: y + 7 = 8 Step 5: y = 1 In which step did Ernesto make the first error? Step 1 Step 2 Step 3 Step 4

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(1) Answers
MorganTyyler

The answer is Step 3: 3y + 7 _ 2y = 8. Ernesto made a mistake in the step 3 because he did not multiply 3 and 7. The correct order of steps is: Step 1: x = y + 7 Step 2: 3(y + 7) - 2y = 8 Step 3: 3y + 3·7 - 2y = 8 Step 4: y + 21 = 8 Step 5: y = - 13

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