Question

Tìm x , biết :

A / ( 2x+1 )^2 - 4 ( x+2 )^2 = 9

B / ( x+3)^2 - ( x-4 ) . ( x+8 ) = 1

C / 3.( x+2 )^2 + ( 2x-1 ) - 7 ( x+3 ) . ( x-3 ) = 36

-- Ai giúp Trân , Trân sẽ tick cho --

Answer 1

\(A.\left(2a+1\right)^2-4\left(a+2\right)^2=9\\ \left(2a+1-2a-4\right)\left(2a+1+2a+4\right)=9\)

\(-3\left(4a+5\right)=9\\ -12a-15=9\\ -12a=24\\ a=-2\)

Answer 2

\(B.\left(a+3\right)^2-\left(a-4\right)\left(a+8\right)=1\\ a^2+6a+9-\left(a^2+8a-4a-32\right)=1\)

\(a^2+6a+9-a^2-4a+32=1\\ 2a=-40\\ a=-20\)