126 x ( a - a ) x a x 26

126 x 0 x a x 26

0

126 x (a x 1 - a : 1) x a x 26

= 126 x 0 x a x 26

= 0

a) 126 x 4 + 126 x 5 + 126

= 126 x 4 + 126 x 5 + 126 x 1

= 126 x ( 4 + 5 + 1 )

= 126 x 10

= 1260

b) 184 x 100 - 50 x 100

= ( 184 - 50 ) x 100

= 134 x 100

= 13400

4 x 126 x 25

= ( 4 x 25 ) x 126

= 100 x 126

= 12600

Đáp án:

4 x 126 x 25

= ( 4 x 25 ) x 126

= 100 x 126

= 12600

Bài 1: Tính nhanh 

A, 13 x 126 + 37 x 126 - 49 x 126

= 126 x ( 13 + 49 - 49 )

= 126 x 1

= 126

B, ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x 102 - 101 x 101 - 50 - 51 )

= ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x ( 102 - 101 - 1))

= ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x 0)

= ( 1 + 2 + 4 + 8+.....+ 512 ) x 0

= 0

a,

b,

 4 x 126 x6

=(4 x 125 + 4 x 1) x 6

=(500 +4)x6

=504 x 6

=3024 

4 x 126 x 6

= 504 x 6

= 3024

Chúc bạn học tốt

a. 4 x 126 x 25

= (4 x 25) x 126

= 100 x 126

= 12600

b. (9 x 8 – 12 – 5 x 12) x ( 1 + 2 + 3 + 4 + 5)

= (72 – 12 – 60) x ( 1 + 2 + 3 + 4 + 5)

= 0 x ( 1 + 2 + 3 + 4 + 5)

= 0

a: Ta có: \(A=126y^3+\left(x-5y\right)\left(x^2+5xy+25y^2\right)\)

\(=126y^3+x^3-125y^3\)

\(=x^3+y^3\)

\(=\left(-5\right)^3+\left(-3\right)^3=-125-27=-152\)

b: \(C=x^3-9x^2+27x-26\)

\(=x^3-9x^2+27x-27+1\)

\(=\left(x-3\right)^3-1=\left(23-3\right)^3-1=20^3-1\)

=8000-1

=7999

c: \(D=\left(2x-3\right)^2+\left(4x-6\right)\left(4-x\right)+\left(x-4\right)^2\)

\(=\left(2x-3\right)^2-2\left(2x-3\right)\left(x-4\right)+\left(x-4\right)^2\)

\(=\left(2x-3-x+4\right)^2=\left(x+1\right)^2\)

\(=\left(99+1\right)^2=100^2=10000\)