Question

把抛物线y=-3(x-1)^2向上平移k个单位,所得抛物线与x轴交于点A（m,0）,点B（n,0）,若m^2+n^2=2

Answer 1

把抛物线y=-3(x-1)^2向上平移k个单位,所得抛物线与x轴交于点A（m,0）,点B（n,0）,若m^2+n^2=26/9,请求出k的值

y=-3(x-1)^2+k

y=-3x^2+6x-3+k

m^2+n^2=26/9

(m+n)^2-2mn=26/9

根据韦达定理

4+1-k/3=26/9

19/9=k/3

k=19/3