Problem: The square of 5−y2−255-\sqrt{y^{2}-25}5−y2−25 is:
Answer Choices:
A. y2−5y2−25y^{2}-5 \sqrt{y^{2}-25}y2−5y2−25
B. −y2-y^{2}−y2
C. y2y^{2}y2
D. (5−y)2(5-y)^{2}(5−y)2
E. y2−10y2−25y^{2}-10 \sqrt{y^{2}-25}y2−10y2−25 Solution:
(5−y2−25)2=25−10y2−25+y2−25=y2−10y2−25\left(5-\sqrt{y^{2}-25}\right)^{2}=25-10 \sqrt{y^{2}-25}+y^{2}-25=y^{2}-10 \sqrt{y^{2}-25}(5−y2−25)2=25−10y2−25+y2−25=y2−10y2−25.