当正方形的边长增加xcm时,其面积为(5+x)² cm²,则y = (5+x)² - 5²y = 25 + 10x + x² - 25y = x² + 10x当x=2cm时,y = 2² + 10*2 = 24cm²当x=3cm时,y = 3² + 10*3 = 39cm...