\(\left(x+2\right)^2-\left(x-1\right)^2=27\)
\(\Leftrightarrow x^2+4x+4-x^2+2x-1-27=0\)
\(\Leftrightarrow6x-24=0\)
\(\Leftrightarrow6x=24\)
\(\Leftrightarrow x=\frac{24}{6}=4\)
Giải :
( x + 2 )2 - ( x - 1 )2 = 27
<=> ( x2 + 4x + 4 ) - ( x2 - 2x + 1 ) = 27
<=> x2 + 4x + 4 - x2 + 2x - 1 =27
<=> 6x + 3 = 27
<=> 6x = 24
<=> x = 4
Vậy bạn chép đi nhá :0
(x+2)\(^{ }\)2-(x-1)2 = 27
(x+2)2 - (x-1)2 =27
(x+2)2 - x2 + 12=27
x2+22 - x2 + 12 = 27
(x2 - x2) + 22 + 12 =27
x+5 = 27
x=27-5
x=22