Project ID:
3000000020
Question:
Maria tried to subtract two polynomials. Her work is shown below: $$ \begin{aligned} (5c^2-7cd+d^2)-(11c^2+3cd-7d^2)&\stackrel{(1)}= 5c^2-7cd+d^2-11c^2+3cd-7d^2 = \cr &\stackrel{(2)}= (5-11)c^2+(-7+3)cd+(1-7)d^2 =\cr &\stackrel{(3)}= -6c^2-4cd-6d^2 \end{aligned} $$
At which step did Maria make a mistake, if she made any at all?
Answer 1:
In step (1). After removing the parentheses, we get the expression: $$5c^2-7cd+d^2-11c^2-3cd+7d^2$$
Answer 2:
In step (2). Combining like terms, we get the expression: $$(5-11)c^2-(7+3)cd+(7+1)d^2$$
Answer 3:
In step (3). Simplified expression after adding coefficients at the like terms is: $$6c^2+4cd+6d^2$$
Answer 4:
Maria's work is correct.
Fixed Answer:
All Fixed
Correct Answer:
Answer 1