a. = 12 - 25 + 36 - 12 + 36 - 57

= (12 - 12) + (36 + 36) - (25 + 57)

= 0 + 72 - 82

= -10

b. = -23 - 5 + 6 - 17 + 23 - 5 - 83 - 6

= (-23 + 23) + (-5 - 5) + (6 - 6) - (17 + 83)

= 0 + (-10) + 0 - 100

= -110

c.?

Ta có:

a(b-c)-c(b-d)+a(c+d)+bc

=ab-ac-bc+cd+ac+ad+bc

=ab+cd+ad

Hok tốt !!!

a( b-c ) - c(b-d) + a(c+d) +bc

= ab -ac - bc + cd + ac + ad + bc

=ab + cd + ad

a)= a-c+d-c+a-d

=2a-2c=2(a-c)

b)=-a-b+c-d+a-b-c-d

=-2b-2d

=2.(-b)-2d=2(-b-d)

c)=ab-ac-ad-ab-ac+ad

=-2.ac

Gấp đến mức độ nào vậy . Bài này đơn giản mà

minh lop 6 sao lam duoc toan lop ?

C1: \(A=\left(\frac{36}{6}-\frac{4}{6}+\frac{3}{6}\right)-\left(\frac{150}{30}+\frac{50}{30}-\frac{45}{30}\right)-\left(\frac{18}{6}-\frac{14}{6}+\frac{15}{6}\right)\)

\(=\frac{35}{6}-\frac{155}{30}-\frac{19}{6}=\frac{35}{6}-\frac{31}{6}-\frac{19}{6}=-\frac{15}{6}=-2\frac{1}{2}\)

C2: \(6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{3}{2}-3+\frac{7}{3}-\frac{5}{2}\)

\(=\left(6-5-3\right)-\left(\frac{2}{3}+\frac{5}{3}-\frac{7}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)\)

\(=-2-0-\frac{1}{2}=-2\frac{1}{2}\)

a-b+a+c nha bn

1)a)=>x²+y²+2xy-4(x²-y²-2xy)

=>x²+y²+2xy-4.x²+4y²+8xy

=>-3.x²+5y²+10xy