1 不等式log½(x²-2x-15)½½>log½(x+13)的解集是_____________2 函数y=(x²+5)/(√x²+4)最小值为________________
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![1 不等式log½(x²-2x-15)½½>log½(x+13)的解集是_____________2 函数y=(x²+5)/(√x²+4)最小值为________________](/uploads/image/z/3762077-5-7.jpg?t=1+%E4%B8%8D%E7%AD%89%E5%BC%8Flog%26%23189%3B%EF%BC%88x%26%23178%3B-2x-15%EF%BC%89%26%23189%3B%26%23189%3B%EF%BC%9Elog%26%23189%3B%EF%BC%88x%2B13%EF%BC%89%E7%9A%84%E8%A7%A3%E9%9B%86%E6%98%AF_____________2+%E5%87%BD%E6%95%B0y%3D%EF%BC%88x%26%23178%3B%2B5%EF%BC%89%2F%EF%BC%88%E2%88%9Ax%26%23178%3B%2B4%EF%BC%89%E6%9C%80%E5%B0%8F%E5%80%BC%E4%B8%BA________________)
1 不等式log½(x²-2x-15)½½>log½(x+13)的解集是_____________2 函数y=(x²+5)/(√x²+4)最小值为________________
1 不等式log½(x²-2x-15)½½>log½(x+13)的解集是_____________
2 函数y=(x²+5)/(√x²+4)最小值为________________
1 不等式log½(x²-2x-15)½½>log½(x+13)的解集是_____________2 函数y=(x²+5)/(√x²+4)最小值为________________
log½(x²-2x-15)>log½(x+13)
即有:(x^2-2x-15)
(x-7)(x+4)<0
-4
x+13>0,x>-13
综上所述,范围是5
设t=根号(x^2+4)>=2
y=t+1/t,在[2,+无穷)上是单调增的,故有最小值是y=2+1/2=5/2
自动忽略)1/2 1/2.。。。。。由不等式log1/2(x2-2x-15)>log1/2x+13)可得 0<x2-2x-15<x+13, 即 x2-2x-15>0 x2-2x-15<x+13 即 (x-5)(x+3)>0 (x+4)(x-7)<0 即 x>5或x<-3-4<x<7由此解得-4<x<-3,或 5<x<7,(
2)由函数可知x要大于或等于2
设t=根号下...
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自动忽略)1/2 1/2.。。。。。由不等式log1/2(x2-2x-15)>log1/2x+13)可得 0<x2-2x-15<x+13, 即 x2-2x-15>0 x2-2x-15<x+13 即 (x-5)(x+3)>0 (x+4)(x-7)<0 即 x>5或x<-3-4<x<7由此解得-4<x<-3,或 5<x<7,(
2)由函数可知x要大于或等于2
设t=根号下x2+4
y=(t2+1)/t
所以y=t2/t+1/t=t+1/t(对勾函数)
由对勾函数图像可知:当x=2时,y有最小值
所以y=2.5
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