First set everything to 0.

Giving you A= 1 , B= 1 and C= -5
Then input everything into the quadratic formula and either solve by hand or use a calculator.
Note exact values are found by hand, decimals are found using a calculator.
They are not proportional
Answer:
answer is 10...hope it helps uh
The sum of the two smallest numbers has to equal a number greater that the largest one. Or, how some people prefer it, the sum of any two numbers of the set has to be a greater number than the third one.
So, the set of sides 7,9,17 does not form a triangle.
because 7+9= 16, which is less than the greatest number, 17.