更新時(shí)間:2024-01-12 16:35:18作者:貝語(yǔ)網(wǎng)校
若A(),B(),C()為二次函數(shù)y=x2+4x-5的圖象上三點(diǎn),則y1,y2,y3的大小關(guān)系為_(kāi)_______<________<________.
y2 y1 y3
此題可根據(jù)給出的二次函數(shù)判斷開(kāi)口方向向上,對(duì)稱(chēng)軸為直線x=-2,再比較圖象上三點(diǎn)到對(duì)稱(chēng)軸的距離,則距離越大,其縱坐標(biāo)越大.
解答:對(duì)二次函數(shù)y=x2+4x-5,a=1>0,開(kāi)口向上,對(duì)稱(chēng)軸為直線x=-2.
又A、B、C三點(diǎn)到對(duì)稱(chēng)軸的距離分別為|--(-2)|=,|--(-2)|=,|-(-2)|=,
∴y2<y1<y3,
故答案是:y2、y1、y3.
點(diǎn)評(píng):本題考查了二次函數(shù)的性質(zhì),重點(diǎn)是判斷函數(shù)的對(duì)稱(chēng)軸,由點(diǎn)到對(duì)稱(chēng)軸的距離比較出各點(diǎn)縱坐標(biāo)的大小.