bayangan garis y = 2x + 3 krna rotasi yg brpusat di (0,0) sebesar π/2 radian adalah...

RotaSI  [ O, π/2 ]
π/2 = 90°


[tex] \left[\begin{array}{ccc}x'\\y'\end{array}\right]\, =\, \left[\begin{array}{ccc}cos\, 90&-sin\,90\\sin\,90&cos\,90\end{array}\right]\,\left[\begin{array}{ccc}x\\y\end{array}\right] [/tex]


[tex] \left[\begin{array}{ccc}x'\\y'\end{array}\right]\, =\, \left[\begin{array}{ccc}0&-1\\1&0\end{array}\right]\,\left[\begin{array}{ccc}x\\y\end{array}\right]\,=\, \left[\begin{array}{ccc}-y\\x\end{array}\right] [/tex]

[tex]\left[\begin{array}{ccc}x'\\y'\end{array}\right]\, \,=\, \left[\begin{array}{ccc}-y\\x\end{array}\right] [/tex]

x' = - y → y = - x'
y' =  x →  x = y'
substitusi  pada y = 2x + 3
(-x ') = 2( y' ) + 3
- x = 2y + 3
2y = -x - 3
atau
x + 2y + 3 = 0