If the graph of the equation y=x^2 -2x-(k+3) does not intersect the x-axis, find the range of values of k.
I dunno how 2 do n i want some elaborations, thx!
math question on equations + graphs
2006-12-12 4:05 am
回答 (3)
2006-12-12 4:30 am
✔ 最佳答案
y=x² -2x-(k+3)∵does not meet the x-axis
∴Δ<0
(-2)^2-4(1)[-(k+3)]<0
4-4(-k-3)<0
4-(-4k-12)<0
4+4k+12<0
4k<-16
k<-4
∴k<-4
2006-12-13 10:20 pm
the meaning of this question is the same as x^2 -2x-(k+3) = 0 does not have real root. that is the discriminant is < 0. The method of solving this problem can be refered to the answers above.
2006-12-12 4:12 am
y=x² -2x-(k+3)
because there is no x-intersect
so Δ<0
(-2)² - 4(1)[-(k+3)]<0
4 + 4(k+3)<0
4(k+4)<0
k+4<0
k< -4
so the range of k is k< -4
because there is no x-intersect
so Δ<0
(-2)² - 4(1)[-(k+3)]<0
4 + 4(k+3)<0
4(k+4)<0
k+4<0
k< -4
so the range of k is k< -4
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