最新数学初二基础知识点实数

编辑:sx_yangk

2014-05-30

最新数学初二基础知识点实数

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X

{√5 X-3√ Y=1}

{√3 X-√5 Y=2}

注:X全部不在根号内

√(1/2x)^2+10/9x^2

=√[1/(4x^2)+10/(9x^2)]

=√49/36x^2

若x>0,=7/(6x)

若x<0,=-7/(6x)

√a^4mb^2n+1

=√(a^2mb^n)^2+1

=a^2mb^n+1

√(4a^5+8a^4)(a^2+3a+2)

=√[4a^4(a+2)][(a+2)(a+1)]

=√[4a^4(a+2)^2(a+1)]

=2a^2(a+2)√(a+1)

. 3√(1/6)-4√(50)+30√(2/3)

答案3√(1/6)-4√(50)+30√(2/3)

= 3×√6/6-4×5√2+30×√6/3

=√6/2-20√2+10√6

①5√8-2√32+√50 =5*3√2-2*4√2+5√2 =√2(15-8+5) =12√2

②√6-√3/2-√2/3 =√6-√6/2-√6/3 =√6/6

③(√45+√27)-(√4/3+√125) =(3√5+3√3)-(2√3/3+5√5) =-2√5+7√5/3

④(√4a-√50b)-2(√b/2+√9a) =(2√a-5√2b)-2(√2b/2+3√a) =-4√a-6√2b

⑤√4x*(√3x/2-√x/6) =2√x(√6x/2-√6x/6) =2√x*(√6x/3) =2/3*x*√6

⑥(x√y-y√x)÷√xy =x√y÷√xy-y√x÷√xy =√x-√y

⑦(3√7+2√3)(2√3-3√7) =(2√3)^2-(3√7)^2 =12-63 =-51

⑧(√32-3√3)(4√2+√27) =(4√2-3√3)(4√2+3√3) =(4√2)^2-(3√3)^2 =32-27 =5

⑨(3√6-√4)?? =(3√6)^2-2*3√6*√4+(√4)^2 =54-12√6+4 =58-12√6

⑩(1+√2-√3)(1-√2+√3) =[1+(√2-√3)][1-(√2-√3)] =1-(√2-√3)^2 =1-(2+3+2√6) =-4-2√6

1. =5√5 - 1/25√5 - 4/5√5 =√5*(5-1/25-4/5) =24/5√5 2.=√144+576 =√720 =12√5

2.)√(8/13)^2-(2/13)^2 = √(8/13+2/13)(8/13-2/13) =(2/13)√15

3.3√(1/6)-4√(50)+30√(2/3) 答案3√(1/6)-4√(50)+30√(2/3) = 3×√6/6-4×5√2+30×√6/3 =√6/2-20√2+10√6

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

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;

4.√a^4mb^2n+1(a、b为正数) [√(a^4mb^2n)]+1(a、b为正数) =a^2mb^n+1;

5.√(4a^5+8a^4)(a^2+3a+2)(a>=0) √[(4a^5+8a^4)(a^2+3a+2)](a>=0) =√[4a^4(a+2)(a+2)(a+1)] =√[(2a^2)^2(a+2)^2(a+1)] =2a^2(a+2)√(a+1).

标签:数学知识点

免责声明

威廉希尔app (51edu.com)在建设过程中引用了互联网上的一些信息资源并对有明确来源的信息注明了出处,版权归原作者及原网站所有,如果您对本站信息资源版权的归属问题存有异议,请您致信qinquan#51edu.com(将#换成@),我们会立即做出答复并及时解决。如果您认为本站有侵犯您权益的行为,请通知我们,我们一定根据实际情况及时处理。