i^4 - 5i^4 - 3√-3 √5

= (i²)² - 5(i²)² - 3√-1 √3 √5 {made i^4 into (i²)² because i² is -1, also broke down the -3}

= (-1)² - 5(-1)² - 3i√15 {evaluated i² to be -1, √-1 to be i, and multiplied the 3 and 5}

= 1 - 5(1) - 3i√15 {squared the -1’s}

= 1 - 5 - 3i√15 {multiplied -5 by 1}

**= -4 - 3i√15 ** {combined like terms}

*- Algebra House*
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