IFRS3 measures the cost of the acquisition at the fair value of the consideration paid; allocates that cost to the acquired identifiable assets and liabilities on the basis of their fair values; allocates the rest of the cost to goodwill; and recognises any excess of acquired assets and liabilities over the consideration paid (a ‘bargain purchase’) in profit or loss immediately

Source: https://www.ifrs.org/issued-standards/list-of-standards/ifrs-3-business-combinations/

The core principle in IAS 36 is that an asset must not be carried in the financial statements at more than the highest amount to be recovered through its use or sale. If the carrying amount exceeds the recoverable amount, the asset is described as impaired. The entity must reduce the carrying amount of the asset to its recoverable amount, and recognise an impairment loss. IAS 36 also applies to groups of assets that do not generate cash flows individually (known as cash-generating units).

Source: https://www.ifrs.org/issued-standards/list-of-standards/ias-36-impairment-of-assets/

IFRS 13 defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (an exit price). When measuring fair value, an entity uses the assumptions that market participants would use when pricing the asset or the liability under current market conditions, including assumptions about risk. As a result, an entity’s intention to hold an asset or to settle or otherwise fulfil a liability is not relevant when measuring fair value.