Tax_query groep/huiswerk

$tax_query = array(
	array(
		'taxonomy'         => 'groepen',
		'terms'            => 'groep-8',
		'field'            => 'slug',
	),
	array(
		'taxonomy'         => 'groepen',
		'terms'            => 'huiswerk',
		'field'            => 'slug',
		'operator'         => 'NOT IN',
	),
);