Question

初一数学计算、去括号、合并同类项、解方程题.(过程要写清楚)

1.计算.
(1)-1.5-(-11.5) (2)4×(-3)²+6
(3)22.5+(-3.3)+(-12.5)+3.3 (4)42×(-2/3)+(-3/4)÷(-0.25)
(5)(-4)-丨-8丨+丨-2丨-(-3) (6)(-3)²×[（-2/3）+（-5/9）]
(7)1/3+1/15+1/35+...+1/9999
2.去括号、合并同类项.
(1)5(2x-7y)-3(4x-10y) (2)(x+y)-[3x+(-x+y)]
3.已知a²+ab＝3,b²+ab=－2
(1)求a²+2ab+b²的值 (2)求a²－b²的值
4.解方程.
(1)2x-5=2 (2)-a/2+3=5
(3)2-3x-1/2=7/2+x-14/3 (4)-2(3-2x)=12

Answer 1

(1)-1.5-(-11.5) =-1.5+11.5=10
(2)4×(-3)²+6=4x9+6=36+6=42
(3)22.5+(-3.3)+(-12.5)+3.3 =22.5-12.5-3.3+3.3=10
(4)42×(-2/3)+(-3/4)÷(-0.25)=-28+3/4x4=-28+3=-25
(5)(-4)-丨-8丨+丨-2丨-(-3)=-4-8+2+3=-7
(6)(-3)²×[（-2/3）+（-5/9）]=9x(-6/9-5/9)=-9x11/9=-11

(1)5(2x-7y)-3(4x-10y)=10x-35y-12x+30y=-2x-5y
(2)(x+y)-[3x+(-x+y)]=x+y-(3x-x+y)=x+y-2x-y=-x

(1)a²+2ab+b²=(a²+ab)+(b²+ab)=3+(-2)=1
(2)a²－b²==(a²+ab)-(b²+ab)=3-(-2)=5

(1)2x-5=2 2x=-3 x=-2/3
(2)-a/2+3=5 -a/2=5-3=2 -a=2x2=4 a=-4
(3)2-3x-1/2=7/2+x-14/3 2-1/2-7/2+14/3=x+3x 8/3=4x x=32/3
(4)-2(3-2x)=12 -3+4x=12 4x=12+3=15 x=4/15