【導(dǎo)讀】有些量的數(shù)值是始終不變的,我們稱它們?yōu)開_______.對于x的________確定的值,y都有________確定的值與其對應(yīng),當(dāng)t=______時,s=0,當(dāng)t=________時,s=200,當(dāng)t=______時,s=350,當(dāng)t=________時,s=800.筆的售價y(元)與圓珠筆的支數(shù)x(支)之間的函數(shù)解析式是什么?解:當(dāng)x=-2時,y=(x+3)(x+2)==0;____________,自變量x的取值范圍是__________________.y=10+0≤x≤16. 4.在函數(shù)y=-3x+5中,當(dāng)x=-1時,y=_______;求每次付款后欠款數(shù)y(萬元)與付款月數(shù)x的函數(shù)解析式;