Question

A student's work to distribute and simplify a radical is shown below. Select the statement which best applies to the sample mathematical work.given (-5√20+√3)*(2+√3), i first distribute to get the expression -10√20-5√60+2√3+√9, which i can simplify to -40√5-20√15+2√3+3 for an answer.Which simplifies to 10 as the answer?
A. The student did not properly distribute the radicals.
B. The student did not properly combine the radicals.
C. The student did not properly simplify the radical at the end.
D. The work shown above is correct.

Answer 1

(-5$\sqrt{20}$ + $\sqrt{3}$) * (2 + $\sqrt{3}$) = 
-10$\sqrt{20}$ - 5$\sqrt{60}$ +2$\sqrt{3}$ + $\sqrt{9}$ = 

$\sqrt{20} = \sqrt{ 2^{2}*5 } = 2 \sqrt{5}$ 

$\sqrt{60} = \sqrt{ 2^{2} * 3 * 5 } = 2 \sqrt{15}$

The problem is the student square root wrongly

The final results is:

-20$\sqrt{5}$ - 10$\sqrt{15}$ + $2 \sqrt{3}$ +3

The right answer for the question above is: 
C. C. The student did not properly simplify the radical at the end.