X squared minus 7XY -98Y squared

Write the fraction 9/50 as a decimal if needed round to the nearest hundredth

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?

Given that y varies directly to the square root of (x + 1), and that y = 1 when x = 8,(a)express y in terms of .x,(b)find the value of y when x = 3,(c)find the value of x when y = 5.