Laravel Return redirect back return to show()

so i have this controller in laravel 5 that contain action from form, and i use

return redirect()->back()->withInput();

for the action handler after the form is submitted, but after i click the form submit action i have this error:

::show() does not exist

can anyone tell me the solution, thank you. This is my route , is it route problem :

Route::post('yudisium/updateblanko/search','Yudisium\UpdateBlankoController@search');
Route::patch('yudisium/updateblanko/{nim}', 'Yudisium\UpdateBlankoController@update');
Route::post('yudisium/updateblanko/update', 'Yudisium\UpdateBlankoController@update');
Route::patch('yudisium/updateblanko2/{nim}', 'Yudisium\UpdateBlankoController@update2');
Route::post('yudisium/updateblanko/update', 'Yudisium\UpdateBlankoController@update2');
Route::resource('yudisium/updateblanko','Yudisium\UpdateBlankoController');

via Chebli Mohamed