We can check by subbing in the values.
7x + 2y = -7
(7,9).....x = 7 and y = 9
now we sub
7(7) + 2(9) = -7
49 + 18 = -7
67 = -7 (incorrect)....therefore, (7,9) is NOT a solution for this equation
1/2*bh=75
1/2*bb=75
b^2=150
b=rt(150)=12.2
not sure what you mean by link, but 12.2 is approximately the length you're seeking
Hey! :)
Some things to note: When you bring a exponent to the numerator, you make it negative.
When you put an exponent to another exponent, you multiply the exponents together.

so that is your answer, please let me know if you need more of an explanation. :)