5.
(2021九上·南昌期末)
拱橋的形狀是拋物線,其函數(shù)關(guān)系式為
, 當(dāng)水面離橋頂?shù)母叨葹?img class="mathml" src="http://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmfrac%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3C%2Fmath%3E" style="max-width:100%;vertical-align: middle;">m時(shí),水面的寬度為( )米.