\(16x^2-\left(4x-5\right)^2=15\)
\(\Leftrightarrow\left(4x\right)^2-\left(4x-5\right)^2-15=0\)
\(\Leftrightarrow\left(4x-4x+5\right)\left(4x+4x-5\right)-15=0\)
\(\Leftrightarrow5\left(8x-5\right)-15=0\)
\(\Leftrightarrow40x-25-15=0\)
\(\Leftrightarrow40x-40=0\)
\(\Leftrightarrow x=1\)
Tìm x, biết:
\(16x^2-\left(4x-5\right)^2=15\)
\(\left(4x\right)^2-\left(4x-5\right)^2-15=0\)
\(\left(4x-4x+5\right)\left(4x+4x-5\right)-15=0\)
\(5\left(8x-5\right)-15=0\)
\(40x-25-15=0\)
\(40x-40=0\)
\(x=1\)
\(16x^2-\left(4x-5\right)^2=15\)
\(\Leftrightarrow\left(4x+4x-5\right)\left(4x-4x+5\right)=15\)
\(\Leftrightarrow5\left(8x-5\right)=15\)
\(\Leftrightarrow8x-5=3\)
\(\Leftrightarrow8x=8\)
\(\Leftrightarrow x=1\)
À mình ghi thiếu dấu \(\Leftrightarrow\) cho mình xin lỗi nhé!
Giải
16x2-(4x-5)2=15
(4x)2-(4x-5)2=15
(4x-4x+5).(4x+4x-5)=15
=>5.(8x-5)=15
8x-5=15\(\div\)5
8x-5=3
8x=8
x=8/8
x=1
Vậy x=1
