Hello can u plz graph this??

Write numerical coefficient of y² in the expression 2x² - 15xy – 7y²

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Given the sequence 7, 14, 28, 56, which expression shown would give the tenth term? a. 7^10 b. 7·2^10 c. 7·2^9