Question

упростите выражение:(c+3)(5-c)-3c(1-c)

Answer 1

$(c+3)(5-c)-3c(1-c)=5c-c ^{2} +15-3c-3c+3c ^{2} = \ =5c-6c+3c ^{2} -c ^{2} +15=-c+2c ^{2} +15=2c ^{2} -c+15$