(21a^3-7a^2+14a)÷(7a)1-(1/3)^-4 ×1/9+8化简求值2a(a-2b)-(a-2b+3)(a+2b-3)-(2b-a)^2,其中a=负根号2,b=1/3

来源:学生作业帮助网 编辑:六六作业网 时间:2024/11/07 16:51:23
(21a^3-7a^2+14a)÷(7a)1-(1/3)^-4×1/9+8化简求值2a(a-2b)-(a-2b+3)(a+2b-3)-(2b-a)^2,其中a=负根号2,b=1/3(21a^3-7a^

(21a^3-7a^2+14a)÷(7a)1-(1/3)^-4 ×1/9+8化简求值2a(a-2b)-(a-2b+3)(a+2b-3)-(2b-a)^2,其中a=负根号2,b=1/3
(21a^3-7a^2+14a)÷(7a)
1-(1/3)^-4 ×1/9+8
化简求值2a(a-2b)-(a-2b+3)(a+2b-3)-(2b-a)^2,其中a=负根号2,b=1/3

(21a^3-7a^2+14a)÷(7a)1-(1/3)^-4 ×1/9+8化简求值2a(a-2b)-(a-2b+3)(a+2b-3)-(2b-a)^2,其中a=负根号2,b=1/3
(21a^3-7a^2+14a)÷(7a)
=3a^2-a+2
(2)
1-(1/3)^-4 ×1/9+8
=1-3^4×1/3^2+8
=1-3^2+8
=9-9
=0
(3)
2a(a-2b)-(a-2b+3)(a+2b-3)-(2b-a)^2
=2a(a-2b)-(a-(2b-3))(a+(2b-3))-(2b-a)^2
=2a(a-2b)-(a^2-(2b-3)^2)-(2b-a)^2
=2a^2-4ab-a^2+(4b^2-12b+9)-(4b^2-4ab+a^2)
=2a^2-4ab-a^2+4b^2-12b+9-4b^2+4ab-a^2
=-12b+9
b=1/3
原式=-4+9=5