(3/8 - x)^3*1/16=50% 

=> (3/8 - x)^3=50% chia cho 1 phần 16 

=> (3/8 - x)^3=8 

=> (3/8 - x)^3=3^3 

=> 3/8 - x=8 

=> x=3/8 - 8 

=> x= - 61/8

nhớ k cho m nha

\(A=\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

nhân A với (3-1) ta có :

\(A=\left(3-1\right)\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\left(3^4-1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\left(3^8-1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\left(3^{16}-1\right)\left(3^{16}+1\right)\)

\(=3^{32}-1\)

\(B=3^{32}+-1=3^{32}-1\)

\(\Rightarrow A=B\)

minh ra 40 gio nhung khong biet dung ko boi vi cau day dang lam thi het thoi gian

Ta có : 1/3 + 5/8 - 7/12 = 8/24 + 15/34 - 14/24

                                     = 23/24 - 14/24

                                     = 23/24 + -14/24

                                      = 9/24

                                       = 3/8

1+2+3+4+5+6+7+8+9

=(1+9)+(2+8)+(3+7)+(4+6)+5

=10+10+10+10+5

=40+5

=45

= (1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5

=10 + 10 + 10 + 10 + 5

= 40 + 5 

= 45

a: \(A=\left(a+3\right)\left(9a-8\right)-\left(a+2\right)\left(9a-1\right)\)

\(=9a^2-8a+27a-24-\left(9a^2-a+18a-2\right)\)

\(=9a^2+19a-24-9a^2-17a+2=2a-22\)

Thay a=-3 vào A, ta được:

\(A=2\cdot\left(-3\right)-22=-6-22=-28\)

b: \(Q=\left(3x-5\right)\left(2x+11\right)-\left(2x+3\right)\left(3x+7\right)\)

\(=6x^2+33x-10x-55-\left(6x^2+14x+9x+21\right)\)

\(=6x^2+23x-55-6x^2-23x-21\)

=-55-21

=-76

=>Q không phụ thuộc vào biến x

Câu a:

A = (a + 3).(9a - 8) - (2+ a)(9a - 1) (1)

Thay a = -3 vào biểu thức (1) ta có:

A = (-3 + 3).(9.3 - 8) - (2 - 3).(9.(-3) - 1)

A = 0.(27 - 8) - (-1).(-27 - 1)

A = 0 + (-28)

A = - 28 (đpcm)

a, 5/6 + 1/2 = 5/6 + 3/6 = 8/6 = 4/3

b, 7/8 + 1/4 = 7/8 + 2/8 = 9/8

c, 5/9 + 3/7 = 35/63 + 27/63 = 62/63