=(5×4×2)×(√ 13)? =2√2- 1√2+ 10√ 10

=40× 13 =(2- 1+ 10)×√2

=520 = 1 1√2

(- 1/2)×(-2/3)×(-3/4)×(-4/5) -3? ×(-3)?

= 1/3×(-3/4)×(-4/5) =-9×9

=- 1/4×(-4/5) =-8 1

= 1/5

Please ask questions if you don't understand, dear ~