Solve for c
(2c+5/-5)(2c+5/-5) + (4c-2/5)(4c-2/5)=20
I will assume you mean:
(2c+5)/-5 * (2c+5)/-5 + (4c-2)/5 * (4c-2)/5 = 20
major difference from what you typed, those brackets are critical
(4c^2 + 20c + 25)/25 + (16c^2 - 16c + 4)/25 = 20
20c^2 + 4c + 29 = 500
20c^2 + 4c - 471 = 0
solve using the formula