Cut a cube for the second time, the volume is: 4 * 4 * 4 = 64;
Cut a cube for the third time, the volume is: 2*2*2=8.
The remaining volume is: 5*6*9-( 125+64+8)=73.
2,3. 14*{60+(60+0. 15*2* 1)+(60+0. 15*2*2)+........+(60+0. 15*2*599)}
=1/2 * 3.14 * (239.6+60) * 600 = 282317.4 mm = 282.3 m (approximate value. )
3360 degrees.
4, x 2-3x+ 1 = 0, so:
x^2=3x- 1。
So x4+3x2+1= (x2) 2+3x2+1= (3x-1) 2+3 (3x-1)+1.
=9x^2-6x+ 1+9x-3+ 1=9x^2+3x- 1=9x^2+x^2= 10x^2,
So x2/(x4+3x2+1) = x2/10x2 =110.