初二数学上册实数

初二数学上册实数实数包括有理数和无理数。其中无理数就是无限不循环小数 , 有理数就包括整数和分数。小编整理了关于初二数学上册实数的概念和实数的计算方法 , 以供同学们参详和练习 !1. 被开方数含有平方因数：分解因数( 准确找到平方因数 )2. 被开方数含有分母：分母变成平方数解方程 3 X-1=2 X求 X5 X-3 Y=13 X-5 Y=2注： X 全部不在根号内(1/2x)2+10/9x2=1/(4x2)+10/(9x2)=49/36x2若 x0,=7/(6x)若 x0,=-7/(6x) a4mb2n+1 =(a2mbn)2+1 =a2mbn+1 (4a5+8a4)(a2+3a+2) =4a4(a+2)(a+2)(a+1)第 1页=4a4(a+2)2(a+1)=2a2(a+2)(a+1). 3(1/6)-4(50)+30(2/3)答案 3(1/6)-4(50)+30(2/3)= 36/6-452+306/3 =6/2-202+10658 -232+50 =5*32-2*42+52 =2(15-8+5) =122 6-3/2-2/3 =6-6/2-6/3 =6/6(45+27) -(4/3+125) =(35+33)-(23/3+55) =-25+75/3(4a -50b)-2(b/2+9a) =(2a-52b)-2(2b/2+3a) =-4a-62b4x*(3x/2-x/6) =2x(6x/2-6x/6) =2x*(6x/3) =2/3*x*6(xy -yx)xy =xyxy-yxxy =x-y(37+23)(23-37) =(23)2-(37)2 =12-63 =-51(32 -33)(42+27) =(42-33)(42+33) =(42)2-(33)2 =32-27 =5(36 -4)? =(36)2-2*36*4+(4)2 =54-126+4 =58-126 (1+2 -3)(1-2+3) =1+(2-3)1-(2-3) =1-(2-3)2 =1-(2+3+26) =-4-261. =55 - 1/255 - 4/55 =5*(5-1/25-4/5)=24/55 2.=144+576=720 =1252.)(8/13)2-(2/13)2 = (8/13+2/13)(8/13-2/13)=(2/13)15第 2页3.3(1/6)-4(50)+30(2/3)答案 3(1/6)-4(50)+30(2/3) =36/6-452+306/3 =6/2-202+1062. (1-根号 2)/2乘以 (1+ 根号 2)/2题是这样的二分之一减根号 2 乘以二分之一加根号2 答案： (1- 根号 2)/2乘以 (1+根号 2)/2 =(1-2)*(1-2)/4 =(1-2)/4 =-1/4 3.(1/2x)2+10/9x2 (1/2x)2+10/9x2 =(x2/4+10x2/9) =(9x2/36+40x2/36) =(49x2/36) =7x/6;4.a4mb2n+1(a 、b 为正数 ) (a4mb2n)+1(a、b 为正数 )=a2mbn+1;5.(4a5+8a4)(a2+3a+2)(a=0)(4a5+8a4)(a2+3a+2)(a=0) =4a4(a+2)(a+2)(a+1) =(2a2)2(a+2)2(a+1) =2a2(a+2)(a+1).第 3页