[1 2] Find an orthonormal basis for the column space of 4 1 02

A tank can be filled by 2 water keys together in 3 hours with 3 quarters. The main key would be able to fill it by itself in 4 hours less than the other one. In how many hours can each key fill the tank separately?

A homeowner wants to build, along his driveway, a garden surrounded by a fence. A rectangular garden has been enclosed along a side of a driveway. The enclosure is bordered by a length of fence along the driveway (a long side), another long side of fence, and two short sides of fence. The side along the driveway is labeled "$6 per foot" while the remaining three sides are labeled "$2 dollars per foot." If the garden is to be 1,800 square feet, and the fence along the driveway costs $6 per foot while on the other three sides it costs only $2 per foot, find the dimensions (in ft) that will minimize the cost. length along the driveway  ft length perpendicular to the driveway      ft Find the minimum cost (in dollars). $

Travis's carpet has an area of 180 square feet. He hires the CarpetPro carpet cleaning service, which is able to clean 9 square feet of his carpet every minute. Therefore, in the first minute, CarpetPro is able to clean 9 square feet of Travis's carpet (leaving 171 square feet remaining to be cleaned). In the second minute, the cleaner is again able to clean 9 square feet of carpet (leaving 162 square feet to be cleaned), etc. Which of the following functions expresses the number of square feet that still remain to be cleaned after t minutes from the time that the carpet cleaner began cleaning this carpet.   A(t)=180−0.9t A(t)=180(0.1)t A(t)=180(0.9t) A(t)=180−9t A(t)=180−0.1t