几道平方计算题,
问题描述：
几道平方计算题,
3×√40-√2/5+2√1/10
(2√3+3√2)(2√3-3√2)
(√6-3√3)^2
5√2+√8-7√8
√30÷√3×√2
答
3×√40-√2/5+2√1/10
=3×2√10-√10/5+2√10/10
=(6-1/5+1/5)√10
=2√10
(2√3+3√2)(2√3-3√2)
=(2√3)^2-(3√2)^2
=12-18
=-6
(√6-3√3)^2
=6-2×√6×3√3+27
=33-6√18
=33-18√2
5√2+√8-7√8
=5√2-6√8
=5√2-12√2
=-7√2
√30÷√3×√2
=√(30÷3×2)
=√20
=2√5