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21. If k is a rational constant not equal to 1, which of the following graphs represents the equation y+5=k(x+y)+5?
22. What is the equation of the line graphed in the xy-plane that passes through the point (-4,-5) and is parallel to the line whose equation is 3x-4y=-8?
23. The equations below are graphed in the xy-plane. Which equation's graph will have a slope of and a y-intercept of 3?
A. 7x+8y=24
B. 7x-8y=-24
C. 8x+7y=3
D. 7x-8y=3
Correct Answer: B Difficult level: 4
24. The equation for the gravitational potential energy U of a 1-kilogram object on Earth resting h meters above the ground t seconds after placement is U = 9.8h joules. Which of the following is a graph of U versus t for a 1-kilogram object 2 meters above the ground?
