Osvaldo's teacher asked him to write an equivalent equation for length, 1, in terms of perimeter, p, and width,
w. He wrote:
Analyze Osvaldo's work to determine where he made
an error and what his error was.
O In step 1, he had to add 2w to both sides.
O In step 1, he had to divide both sides by 2w
O In step 2, he had to divide both sides by 2.
O In step 2, he had to subtract 2 from both sides.
p = 21 + 2w
His steps to solve were:
1.
Subtract 2w.
p - 2w = 21
2. Multiply by 2.
2(p - 2w) = 1
His equivalent equation was l = 2(p - 2w).