Answer:
c = 30
Step-by-step explanation:
since:
[tex]{(10)}^{2} = { (- 10)}^{2} [/tex]
once we find a c value for 10, we know that it will work for - 10 as well
[tex] {x}^{2} - c = 70[/tex]
we can sub in 10 to get
[tex] {10}^{2} - c = 70 \\ c = 100 - 70 \\ c = 30[/tex]
