化简求值:2a-3(a-2b)[1-5(2a-b)],其中a=1,b=-5

---

原式尘衡=2a-[3(a-2b)-15(2a-b)(a-2b)]
=2a-[3a-6b-30a^2+75ab-30b^2]
=2a-3a+6b+30a^2-75ab+30b^2
=-a+6b+30a^2-75ab+30b^2
当a=1,b=-5时
原派竖做式纤迹=-1-30+30+75×5+30×25
=1124

---

2a-3(a-2b)[1-5(2a-b)]
=(5a+6b)(1-10a+5b)
=(5-30)(1-10-25)
=-25*(-34)
=850

---

不化解的话直接带进去最简单

---