732 – 272

= (73 + 27)(73 – 27)

= 100.46

= 4600

87 2  +  73 2  –  27 2  -  13 2  = ( 87 2  –  13 2 ) + ( 73 2  –  27 2 )

      = (87 + 13)(87 – 13) + (73 + 27)(73 – 27)

      = 100.74 + 100.46 = 100(74 + 46) = 100.120 = 12000

a) 4600.              b) 1100.

c) 8100.              d) 7200.

Bài 1:

a. 

$=(x^3+2^3)-(x^3-2)=2^3+2=10$

b.

$=(x^2+10x+25)-4x(4x^2+12x+9)-(2x-1)(x^2-9)$
$=x^2+10x+25-16x^3-48x^2-36x-(2x^3-18x-x^2+9)$

$=-18x^3-46x^2-8x+16$

2.

a. 

$301^2=(300+1)^2=300^2+2.300+1=90000+600+1$

$=90601$

b.

$198^2=(200-2)^2=4(100-1)^2=4(100^2-2.100+1)$

$=4(10000-200+1)=4.9801=39204$

c.

$93.107=(100-7)(100+7)=100^2-7^2$

$=10000-49=9951$

d.

$127^2+146.127+73^2$

$=127^2+2.73.127+73^2$
$=(127+73)^2=200^2=40000$

(589-732)-(589+2011-732)

= 589-732-589-2011+732

= (589-589)+(732-732)-2011

= 0+0-2011

=-2011

\(\left(589-732\right)-\left(589+2011-732\right)\)

\(=589-732-589-2011+732\)

\(=\left(589-589\right)+\left(-732+732\right)-2011\)

\(=-2011\)

thiếu r

4,25 . 5 .20

=425

\(425\)

a) = (50-1)^2 = 50^2 - 2.50 + 1 = 2500 - 100 + 1 = 2401

b) = (50+1)^2 = 50^2 + 2.50 + 1 = 2601

c) = 9900

a) \(\left(-48\right)+10+\left(-22\right)+\left(-10\right)\)

\(=\left[\left(-48\right)+\left(-22\right)\right]+\left(-10+10\right)\)

\(=-70+0=-70\)

Tham khảo <3

= -70 

( hihi )

(-48)+(-22)+(10-10)

=-70 +0

=-70

\(a.75^2-50.75+25^2\\ =75^2-2.25.75+25^2\\ =\left(75-25\right)^2=50^2=2500\)

\(b.103.97\\ =\left(100+3\right)\left(100-3\right)\\ =100^2-3^2\\ =9991\)

\(a,75^2-50.75+25^2\\ =75^2-2.75.25+25^2\\ =\left(75+25\right)^2=100^2=10000\\ b,103.97\\ =\left(100+3\right).\left(100-3\right)\\ =100^2-3^2=10000-9=9991\)

a) \(75^2-2\cdot25\cdot75+25^2\)

= \(\left(75+25\right)^2\)

= \(100^2=10000\)
b) \(103\cdot97\)

= \(\left(100+3\right)\left(100-3\right)\)

= \(100^2-3^2\)

= \(10000-9=9991\)