P=x3+y3+2xy=(x+y)3−3xy(x+y)+2xy=2013−601xy" role="presentation" style="border:0px; direction:ltr; display:inline-block; float:none; font-size:16.38px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">P=x3+y3+2xy=(x+y)3−3xy(x+y)+2xy=2013−601xy

S=xy=x(201−x)" role="presentation" style="border:0px; direction:ltr; display:inline-table; float:none; font-size:16.38px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">S=xy=x(201−x)

1≤x≤200" role="presentation" style="border:0px; direction:ltr; display:inline-block; float:none; font-size:16.38px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">1≤x≤200

S=200−(x−1)(x−200)≥0⇒Smin=200" role="presentation" style="border:0px; direction:ltr; display:inline-block; float:none; font-size:16.38px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">S=200−(x−1)(x−200)≥0⇒Smin=200

x≤y⇒x≤100" role="presentation" style="border:0px; direction:ltr; display:inline-block; float:none; font-size:16.38px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">x≤y⇒x≤100

S=100.101−(x−100)(x−101)≤100.101⇒Smax=100.101" role="presentation" style="border:0px; direction:ltr; display:inline-block; float:none; font-size:16.38px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:1px 0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax_CHTML mjx-chtml">S=100.101−(x−100)(x−101)≤100.101⇒Smax=100.101

\(M=x^{10}-25x^9+25x^8-25x^7+...-25x^3+25x^2-25x+25\)

Ta thấy : \(x=24\Rightarrow x+1=25\)

\(\Rightarrow M=x^{10}-\left(x+1\right)x^9+\left(x+1\right)x^8-\left(x+1\right)x^7+...-\left(x+1\right)x^3+\left(x+1\right)x^2-\left(x+1\right)x+\left(x+1\right)\)

\(M=x^{10}-x^{10}-x^9+x^9+x^8-x^8-x^7+...-x^4-x^3+x^3+x^2-x^2-x+x+1\)

\(\Rightarrow M=1\)

Vậy \(M=1\left(tạix=24\right)\)

ta có: 20=21-1=x-1

B=x⁶-20x⁵-20x⁴-20x³-20x²-20x+3 

= x⁶-(x-1)x⁵-(x-1)x⁴-(x-1)x³-(x-1)x²-(x-1)x+3 

=x⁶-x⁶+x⁵-x⁵+x⁴-x⁴+x³-x³+x²-x²+x+3

=x+3

=21+3

=24

x=21

=>x-1=20

B=x^6-x^5(x-1)-x^4(x-1)-...-x(x-1)+3

=x^6-x^6+x^5-x^5+x^5-...-x^2+x+3

=x+3

=21+3=24

a) 4 500 : 90 : 25 = 50 : 25 = 2

b) 840 : (3 x 4) = 840 : 12 = 70

c) 682 + 96 : 12 = 682 + 8 = 690

d) 2 784 : 24 – 16 = 116 – 16 = 100

a) \(A=\left(-10\right)+\left(-34\right)+\left(-26\right)\)

         \(=\left(-10\right)+\left[\left(-34\right)+\left(-26\right)\right]\)

         \(=\left(-10\right)+\left(-60\right)\)

         \(=-70\)

a) A = ( -34 + -26 ) + (-10)

      =  -60 - 10

        =-70

b) B = 12+35

     =  47

a) = -70
b) = 23

a) \(36 – 18:6 = 36 – 3 = 33\)

b) \(2.3^{2} + 24 : 6 . 2 = 2.9 + 4.2 = 18 + 8 = 26\)

c) \(2.3^{2} – 24 : (6.2) = 2.9 - 24 : 12 = 18 - 2 = 16.\)

 a, 36-18:6=33                                                                    b, 2.3\(^2\)+24:6.2=26                                                            c,2.3²-24:(.2)=16

Lời giải:

$M=(x^{10}-24x^9)-(x^9-24x^8)+(x^8-24x^7)-(x^7-24x^6)+(x^6-24x^5)-(x^5-24x^4)+(x^4-24x^3)-(x^3-24x^2)+(x^2-24x)-(x-24)+1$

$=x^9(x-24)-x^8(x-24)+x^7(x-24)-.....+x(x-24)-(x-24)+1$

$=(x-24)(x^9-x^8+x^7-...+x-1)+1$

$=0.(x^9-x^8+....+x-1)+1=1$

20x2+20x3+20x4+20 

= 200

20 x 2 + 20 x 3 + 20 x 4 +20

=40 + 60 + 80 + 20

=100+80+20

=180+20

=200

Trả lời :

200

Hokt~

:)

Ta có

P = x 10   –   13 x 9   +   13 x 8   –   13 x 7   +   …   -   13 x   +   10

=   x 10   –   12 x 9   –   x 9   +   12 x 8   +   x 8   –   12 x 7   –   x 7   +   12 x 6   +   …   + x 2   –   12 x   –   x   +   10     =   x 9 ( x   –   12 )   –   x 8 ( x   –   12 )   +   x 7 ( x   –   12 )   -   …   +   x ( x   –   12 )   –   x   +   10

Thay x = 12 vào P ta được

P   =   12 9 . ( 12   –   12 )   –   12 8 ( 12   –   12 )   +   12 7 ( 12   –   12 )             -   …   +   12 ( 12   –   12 )   –   12   +   10

= 0 + … + 0 – 2 = -2

Vậy P = -2

Đáp án cần chọn là: A