1、(3x+2)(3x-2)-5x(x-1)-(2x-1)^2 ,其中x=-1/3 先化简,在求值 2、999^2-1000*998 3.比较大小:(1) 4^2+3^2____2*3*4 (-2)^2+1^2____2*(-2)*1 6^2+7^2______2*6*7 3^2+3^2_____2*3*3 (2/3)^2 +(-1)^2_____2*2/3*(-1) (2/3)^2+(2/3)^2_____2*2/3*2/3
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![1、(3x+2)(3x-2)-5x(x-1)-(2x-1)^2 ,其中x=-1/3 先化简,在求值 2、999^2-1000*998 3.比较大小:(1) 4^2+3^2____2*3*4 (-2)^2+1^2____2*(-2)*1 6^2+7^2______2*6*7 3^2+3^2_____2*3*3 (2/3)^2 +(-1)^2_____2*2/3*(-1) (2/3)^2+(2/3)^2_____2*2/3*2/3](/uploads/image/z/1989675-27-5.jpg?t=1%E3%80%81%EF%BC%883x%2B2%EF%BC%89%283x-2%29-5x%28x-1%29-%282x-1%29%5E2+%2C%E5%85%B6%E4%B8%ADx%3D-1%2F3+%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%9C%A8%E6%B1%82%E5%80%BC+2%E3%80%81999%5E2-1000%2A998+3.%E6%AF%94%E8%BE%83%E5%A4%A7%E5%B0%8F%EF%BC%9A%281%29+4%5E2%2B3%5E2____2%2A3%2A4+%28-2%29%5E2%2B1%5E2____2%2A%28-2%29%2A1+6%5E2%2B7%5E2______2%2A6%2A7+3%5E2%2B3%5E2_____2%2A3%2A3+%282%2F3%29%5E2+%2B%28-1%29%5E2_____2%2A2%2F3%2A%28-1%29+%282%2F3%29%5E2%2B%282%2F3%29%5E2_____2%2A2%2F3%2A2%2F3)
1、(3x+2)(3x-2)-5x(x-1)-(2x-1)^2 ,其中x=-1/3 先化简,在求值 2、999^2-1000*998 3.比较大小:(1) 4^2+3^2____2*3*4 (-2)^2+1^2____2*(-2)*1 6^2+7^2______2*6*7 3^2+3^2_____2*3*3 (2/3)^2 +(-1)^2_____2*2/3*(-1) (2/3)^2+(2/3)^2_____2*2/3*2/3
1、(3x+2)(3x-2)-5x(x-1)-(2x-1)^2 ,其中x=-1/3 先化简,在求值
2、999^2-1000*998
3.比较大小:(1) 4^2+3^2____2*3*4
(-2)^2+1^2____2*(-2)*1
6^2+7^2______2*6*7
3^2+3^2_____2*3*3
(2/3)^2 +(-1)^2_____2*2/3*(-1)
(2/3)^2+(2/3)^2_____2*2/3*2/3
(2)从上面这些算式中,你发现了什么规律?你能用含字母的式子揭示这一道理吗?
1、(3x+2)(3x-2)-5x(x-1)-(2x-1)^2 ,其中x=-1/3 先化简,在求值 2、999^2-1000*998 3.比较大小:(1) 4^2+3^2____2*3*4 (-2)^2+1^2____2*(-2)*1 6^2+7^2______2*6*7 3^2+3^2_____2*3*3 (2/3)^2 +(-1)^2_____2*2/3*(-1) (2/3)^2+(2/3)^2_____2*2/3*2/3
(1)
(3x+2)(3X-2)-5x(x-1)-(2x-1)2
=9X^2-4-5X^2+5X-(2x-1)^2
=4X^2-(2x-1)^2-4+5X
=(2X-2X+1)(2X+2X-1)-4-5X
=4X-1-4-5X
=-X-5
把X=三分之一代入
得 该式等于-16/3
(2)
999^2-1000*998
=999^2-(999+1)(999-1)
=999^2-(999^-1)
=1
(3)
大于 大于 大于 等于 大于 大于
n^2+m^2 大于等于 2*m*n
因为
a^2-2ab+b^2=(a-b)^2
(a-b)^2>=0
所以
a^2-2ab+b^2>=0
a^2+b^2>=2ab
1. 9 x^2-4-5x^+5x-4x^2-1+4x=9x-4=3-4=-1