Project ID:
3000000021
Question:
Tesa tried to subtract two polynomials. Her work is shown below: $$ \begin{aligned} (x+4)^2-(x-2)^2&\stackrel{(1)}= (x^2+16)-(x^2-4) = \cr &\stackrel{(2)}= x^2+16-x^2+4 =\cr &\stackrel{(3)}= 20 \end{aligned} $$
At which step did Tesa make a mistake, if she made any at all?
Answer 1:
In step (1). After squaring the parentheses, we get the expresion: $$(x^2+8x+16)-(x^2-4x+4)$$
Answer 2:
In step (2). Be removing the parentheses, we get: $$x^2+16-x^2-4$$
Answer 3:
In step (3). Combining like terms, the expression simplifies to: $$2x^2+20$$
Answer 4:
Tesa's work is correct.
Fixed Answer:
All Fixed
Correct Answer:
Answer 1