b

was not

???

\(a)(2x-1)^2-(4x+1)(x-3)=0 \\4x^2-4x+1-4x^2+11x+3=0 \\7x=-4 \\ x=\dfrac{-4}{7}\\ b)5x(x-3)-2x+6=0\\ 5x(x-3)-2(x-3)=0 \\(5x-2)(x-3)=0 \\x=3\ hoặc\ x=\dfrac{2}{5} \)

B

D

\(​​​M=(4+4^2)+(4^3+4^4)+...+(4^{15}+4^{16}) \\=4(1+4)+4^3(1+4)+...+4^{15}(1+4) \\=5(4+4^3+...+4^{15})\)

--> M chia hết cho 5 (đpcm)

a) 1 - 2x = 5

2x = -4

x = -2

b) 11 - 5x = 21

5x = -10

x = -2

c) x \(\in\){-13; -1; 1; 13}

C