Question

A set of equations is given below: Equation A: y = x + 1 Equation B: y = 4x + 5 Which of the following steps can be used to find the solution to the set of equations? Ax+1 = 4x + 5 B x = 4x + 5 Cx+1 = 4x Dx+5= 4x + 1​

Answer 1

Answer: x+1 = 4x+5 (choice A)

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Work Shown:

y = 4x+5 .... start with equation B

x+1 = 4x+5 .... replace y with x+1, due to equation A

The second step used the substitution property.

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Alternative Viewpoint:

The variable y is equal to both 4x+5 and x+1 at the same time; therefore, the two right hand sides must be the same.

It's like saying if y = x and y = 5, then x = 5.