初二数学上册实数
<p>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!</p><p>1.被开方数含有平方因数：分解因数(准确找到平方因数)</p><p>2.被开方数含有分母：分母变成平方数</p><p>解方程3 X-1=2 X</p><p>求X</p><p>{5 X-3 Y=1}</p><p>{3 X-5 Y=2}</p><p>注：X全部不在根号内</p><p>(1/2x)^2+10/9x^2</p><p>=</p><p>=49/36x^2</p><p>若x0,=7/(6x)</p><p>若x0,=-7/(6x)</p><p>a^4mb^2n+1</p><p>=(a^2mb^n)^2+1</p><p>=a^2mb^n+1</p><p>(4a^5+8a^4)(a^2+3a+2)</p><p>=[(a+2)(a+1)]</p><p>=</p><p>=2a^2(a+2)(a+1)</p><p>. 3(1/6)-4(50)+30(2/3)</p><p>答案3(1/6)-4(50)+30(2/3)</p><p>= 36/6-452+306/3</p><p>=6/2-202+106</p><p>①58-232+50 =5*32-2*42+52 =2(15-8+5) =122</p><p>②6-3/2-2/3 =6-6/2-6/3 =6/6</p><p>③(45+27)-(4/3+125) =(35+33)-(23/3+55) =-25+75/3</p><p>④(4a-50b)-2(b/2+9a) =(2a-52b)-2(2b/2+3a) =-4a-62b</p><p>⑤4x*(3x/2-x/6) =2x(6x/2-6x/6) =2x*(6x/3) =2/3*x*6</p><p>⑥(xy-yx)xy =xyxy-yxxy =x-y</p><p>⑦(37+23)(23-37) =(23)^2-(37)^2 =12-63 =-51</p><p>⑧(32-33)(42+27) =(42-33)(42+33) =(42)^2-(33)^2 =32-27 =5</p><p>⑨(36-4)?? =(36)^2-2*36*4+(4)^2 =54-126+4 =58-126</p><p>⑩(1+2-3)(1-2+3) = =1-(2-3)^2 =1-(2+3+26)=-4-26</p><p>1. =55 - 1/255 - 4/55 =5*(5-1/25-4/5) =24/55 2.=144+576 =720=125</p><p>2.)(8/13)^2-(2/13)^2 = (8/13+2/13)(8/13-2/13) =(2/13)15</p><p>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+106</p><p>2. (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</p><p>3.(1/2x)^2+10/9x^2 [(1/2x)^2+10/9x^2] =(x^2/4+10x^2/9)=(9x^2/36+40x^2/36) =(49x^2/36) =7x/6;</p><p>4.a^4mb^2n+1(a、b为正数) [(a^4mb^2n)]+1(a、b为正数) =a^2mb^n+1;</p><p>5.(4a^5+8a^4)(a^2+3a+2)(a=0) [(4a^5+8a^4)(a^2+3a+2)](a=0)= =[(2a^2)^2(a+2)^2(a+1)] =2a^2(a+2)(a+1).</p>
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