a)2x²-2xy

b)9-x²

c)10012

(Câu c là sao?)

a) \(2x\left(x-y\right)=2x^2-2xy\)

b) \(\left(3+x\right)\left(3-x\right)=3^2-x^2=9-x^2\)

Các bạn giúp mik đi ạ, mik đang cần gấp nhất là câu c ạ

=1476 nhé

chúc bnạ học tốt

TL

123 x 11 + 123 

=123 x (11+1)

=123 x 12

=1476

123 x 11+123

=1353+123

=1476

HT

\(a,123\times54+27\times123-12\times123+123\times31\)

\(=123\times\left(54+27-12+31\right)\)

\(=123\times100\)

\(=12300\)

\(b,\dfrac{121}{27}\times\dfrac{54}{11}< n< \dfrac{100}{21}:\dfrac{25}{126}\)

\(22< n< \dfrac{100}{21}\times\dfrac{126}{25}\)

\(22< n< 24\)

Vì \(23>22\) và \(23< 24\) nên \(n=23\)

a, 123x(54+27-12+31)

=123x100

=12300

a123x54+27x123-12x123+123x31

=123:54+27:123-12:123+123:31

=6642+27:123-12:123+123:31

=6642+3321-12:123+123:31

=6642+3321-1476+123:31

=6642+3321-1476+3813

=12300

b,121/27x54/11<n>100/21:25/126

=22<n>24

n=23

\(\Leftrightarrow\dfrac{5}{4}\left(\dfrac{4}{3\cdot7}+\dfrac{4}{7\cdot11}+...+\dfrac{4}{x\left(x+4\right)}\right)=\dfrac{50}{123}\)

=>(1/3-1/7+1/7-1/11+...+1/x-1/x+4)=50/123:5/4=50/123*4/5=40/123

=>1/3-1/x+4=40/123

=>1/x+4=1/123

=>x+4=123

=>x=119

11 + 22 + ( \(x\) x 2 + \(x\) x 199 ) : 33 = 123 x 123

                 33 + \(x\) ( 2 + 199) : 33  = 15129

                                    201\(x\) : 33  = 15129 - 33

                                    201\(x\) : 33 = 15096

                                    201\(x\)        = 15096 x 33

                                    201\(x\)        = 498168

                                          \(x\)        = 498168 : 201

                                          \(x\)        = 166056/67

98 x 456 x 123 x 753 x 246 x 2222 x 11 x 11 x 11 x 25 x 36 x 25 x 12 x 13 x 159 x 487 x 258 x 12589 x 1524 x ( 36987 - 36987 ) = 0

:)))

98 x 456 x 123 x 753 x 246 x 2222 x 11 x 11 x 11 x 25 x 36 x 25 x 12 x 13 x 159 x 487 x 258 x 12589 x 1524 x ( 36987 - 36987 ) =0

ht

k mk nha

98 x 456 x 123 x 753 x 246 x 2222 x 11 x 11 x 11 x 25 x 36 x 25 x 12 x 13 x 159 x 487 x 258 x 12589 x 1524 x ( 36987 - 36987 ) 

=>0

ht 

= 1353 

123.11=123.10+123=1230+123=1353

123 x 11 = 

1353