What value for c will make the expression a perfect square trinomial x2-7x+c

Segment xy is dilated through point m with a scale factor of 2. which segment shows the correct result of the dilation

Need on this geometry question. explain how you did it.

The swimming pool is open when the high temperature is higher than 20∘c. lainey tried to swim on monday and thursday (which was 3 days later). the pool was open on monday, but it was closed on thursday. the high temperature was 30∘c on monday, but decreased at a constant rate in the next 3 days. write an inequality to determine the rate of temperature decrease in degrees celsius per day, d, from monday to thursday.