初二数学题:关于科学计数法,解方程,因式分解的问题
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/08/24 09:06:13
我要科学计数法10道练习
![](http://img.wesiedu.com/upload/5/06/50687f744358f078c6db70d8d8f65471.jpg)
![](http://img.wesiedu.com/upload/5/06/50687f744358f078c6db70d8d8f65471.jpg)
解题思路: 本题主要根据计算法则进行解答即可求出结果
解题过程:
(1)58000000
(2)110000000
(3)150000000
(4)230000000
(5)780000000
(6)1500000000
(7)2900000000
(8)4500000000
(9)5900000000 (10)87000000000 方程两边同时加上或者减去相同的数,等式保持不变.
x + 0.58 = 12.64 3.2 + x = 10.8 x - 6.2 = 7.8 x - 1.5 = 4
方程两边同时乘上或者除以相同的数,等式保持不变.
5x =6.5 0.2x = 6.2 x ÷ 3.2 = 2.5 x ÷ 6 = 10.9
先把几x看作一个整体.
2x +3.8 = 22 4x - 7.5 = 12.5 9.5 + 6x = 15.5
先把括号里的数看作一个整体.
(x - 3) ÷4 = 7.5 5(1.5 + x) =12.5 10(x - 2.6) = 78
先算出一部分.
3 x + 2.5 × 4 = 31 6.3 ÷ 9 + 2x = 22.1 5x - 2.1× 2 = 6.6
运用乘法分配律.
3.4x +5.4x = 17.6 7x - 3x = 6.8 13.2x +9x 33.3 x - 0.2x = 5.6
未知数是减数或是除数的
17.3 - x = 9.6 28.6÷ x = 11 52.04 - 2x = 30.04 13×2 - 0.5x = 14 (1) 6x4y2-12x3y+27x2y3 =3x2y·2x2y-3x2y·4x+3x2y·9y2=3x2y(2x2y-4x+9y2)
(2)-x4y+x3y2-x2y3=-(x4y-x3y2+x2y3)
=-(x2y·x2-x2y·xy+x2y·y2)
=-x2y(x2-xy+y2)
(3)xn+3xn-1+xn-2=xn-2·x2+xn-2·3x+xn-2·1
=xn-2(x2+3x+1)
(4)5(x-y)3+10(y-x)2=5(x-y)3+10(x-y)2
=5(x-y)2(x-y+2)
(5)m(5ax+ay-1)-m(3ax-ay-1)
=m[(5ax+ay-1)-(3ax-ay-1)]
=m·(5ax+ay-1-3ax+ay+1)
=m(2ax+2ay)=2ma(x+y)
(6)x2+14x+49=x2+2·x·7+72
=(x+7)2
(7)(m+n)2-6(m+n)+9=(m+n-3)2
(8)-3ax2+6axy-3ay2=-3a(x2-2xy+y2)
=-3a(x-y)2
(9)(x2+4)2+8x(x2+4)+16x2
=(x2+4)2+2·(x2+4)·4x+(4x)2
=(x2+4+4x)2
=(x+2)4
(10)64m2n2-(m2+16n2)2
=(8mn)2-(m2+16n2)2
=(8mn+m2+16n2)(8mn-m2-16n2)
=(m+4n)2[-(m-4n)2]
=-(m+4n)2(m-4n)2
解题过程:
(1)58000000
(2)110000000
(3)150000000
(4)230000000
(5)780000000
(6)1500000000
(7)2900000000
(8)4500000000
(9)5900000000 (10)87000000000 方程两边同时加上或者减去相同的数,等式保持不变.
x + 0.58 = 12.64 3.2 + x = 10.8 x - 6.2 = 7.8 x - 1.5 = 4
方程两边同时乘上或者除以相同的数,等式保持不变.
5x =6.5 0.2x = 6.2 x ÷ 3.2 = 2.5 x ÷ 6 = 10.9
先把几x看作一个整体.
2x +3.8 = 22 4x - 7.5 = 12.5 9.5 + 6x = 15.5
先把括号里的数看作一个整体.
(x - 3) ÷4 = 7.5 5(1.5 + x) =12.5 10(x - 2.6) = 78
先算出一部分.
3 x + 2.5 × 4 = 31 6.3 ÷ 9 + 2x = 22.1 5x - 2.1× 2 = 6.6
运用乘法分配律.
3.4x +5.4x = 17.6 7x - 3x = 6.8 13.2x +9x 33.3 x - 0.2x = 5.6
未知数是减数或是除数的
17.3 - x = 9.6 28.6÷ x = 11 52.04 - 2x = 30.04 13×2 - 0.5x = 14 (1) 6x4y2-12x3y+27x2y3 =3x2y·2x2y-3x2y·4x+3x2y·9y2=3x2y(2x2y-4x+9y2)
(2)-x4y+x3y2-x2y3=-(x4y-x3y2+x2y3)
=-(x2y·x2-x2y·xy+x2y·y2)
=-x2y(x2-xy+y2)
(3)xn+3xn-1+xn-2=xn-2·x2+xn-2·3x+xn-2·1
=xn-2(x2+3x+1)
(4)5(x-y)3+10(y-x)2=5(x-y)3+10(x-y)2
=5(x-y)2(x-y+2)
(5)m(5ax+ay-1)-m(3ax-ay-1)
=m[(5ax+ay-1)-(3ax-ay-1)]
=m·(5ax+ay-1-3ax+ay+1)
=m(2ax+2ay)=2ma(x+y)
(6)x2+14x+49=x2+2·x·7+72
=(x+7)2
(7)(m+n)2-6(m+n)+9=(m+n-3)2
(8)-3ax2+6axy-3ay2=-3a(x2-2xy+y2)
=-3a(x-y)2
(9)(x2+4)2+8x(x2+4)+16x2
=(x2+4)2+2·(x2+4)·4x+(4x)2
=(x2+4+4x)2
=(x+2)4
(10)64m2n2-(m2+16n2)2
=(8mn)2-(m2+16n2)2
=(8mn+m2+16n2)(8mn-m2-16n2)
=(m+4n)2[-(m-4n)2]
=-(m+4n)2(m-4n)2