Question

帮我弄几个式子 化简求值的.

(a-3b)^2+(3b+b)^2-(a+5b^2) a=8 b=-6 3a(2a^2-4a+3)-2a^2(3a+4) a=-2 (3x^4-2x^3)÷（-x)-(x-x^2)×3x x=负二分之一 [(ab+1)(ab-2)-2a^2b^2+2]÷(-ab) a=二分之三b=负三分之四

Answer 1

(a-3b)^2+(3a+b)^2-(a+5b^2)
=a²-6ab+9b²+9a²+6ab+b²-a²-10ab-25b²
=9a²-10ab-15b²
=9*8²-10*8*6-15*6²
=576-480-540
=-444

3a(2a^2-4a+3)-2a^2(3a+4)
=6a³-12a²+9a-6a³-8a²
=-20a²+9a
=-20*(-2)²+9*(-2)
=-80-18
=-98

(3x^4-2x^3)÷（-x)-(x-x^2)×3x
=-3x³+2x²-3x²+3x³
=-x²
=-(-1/2)²
=-1/4

[(ab+1)(ab-2)-2a^2b^2+2]÷(-ab)
=[a²b²-ab-2-2a²b²+2]÷(-ab)
=[-a²b²-ab]÷(-ab)
=ab+1
=(-3/2)*(-4/3)+1
=2+1
=3

Answer 2

(a-3b)^2+(3b+b)^2-(a+5b^2)
=a^2-6ab+9b^2+16b^2-a-5b^2
=a^2-6ab-a+20b^2
=8^2-6*8*-（-6）-8+20*6*6
=64-48+6+720
=742

3a(2a^2-4a+3)-2a^2(3a+4)

=6a^3-4a^2+9a-6a^3-8a^2
=-12a^2+9a
=-66

(3x^4-2x^3)÷（-x)-(x-x^2)×3x

=3x^3-2x^2-4x^2+3x^3
=6x^3-6x^2
=9/2

[(ab+1)(ab-2)-2a^2b^2+2]÷(-ab)

=[a^2b^2-ab-2-2a^2b^2+2]÷(-ab)
=[-a^2b^2]÷(-ab)
=ab
=2/3*(-3/4)
=-1/2