Answer:
168.25
Step-by-step explanation:
Do the inside of the parentheses first then multiply then add.
3(56)+.25
168+.25=168.25
x=5 and 3
x^2-8x+21=6
x^2-8x+21+16=6+16
(x-4)^2=1
(x-4)=±1, x=5 and 3
Answer: its called a additive inverse