Question

tìm x biết:

3(x+2)^2 + (2x-3)^2 - 7(x-4)(x+4 ) = 64

Answer 1

\(3\left(x+2\right)^2+\left(2x-3\right)^2-7\left(x-4\right)\left(x+4\right)=64\)

\(\Leftrightarrow3\left(x^2+4x+4\right)+\left(4x^2-12x+9\right)-7\left(x^2-16\right)=64\)

\(\Leftrightarrow3x^2+12x+12+4x^2-12x+9-7x^2+112=64\)

\(\Leftrightarrow12+9+112=64\)(vô lí)

Vậy pt vô nghiệm

Answer 2

 TL:

\(\Leftrightarrow3\left(x^2+4x+4\right)+4x^2-6x+9-7x^2+112=64\)

\(\Leftrightarrow6x+133=64\)  

\(\Leftrightarrow6x=-69\) 

\(\Leftrightarrow x=\frac{-23}{2}\) 

Vậy....

Answer 3

Nguyễn Văn Tuấn AnhSai từ dòng đầu tiên

\(\left(2x-3\right)^2=4x^2-12x+9\ne4x^2-6x+9\)