使函数y=4^x*a+2^x+1在x属于(-无穷大,1】上y>0恒成立,求a的范围
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![使函数y=4^x*a+2^x+1在x属于(-无穷大,1】上y>0恒成立,求a的范围](/uploads/image/z/11486521-1-1.jpg?t=%E4%BD%BF%E5%87%BD%E6%95%B0y%3D4%5Ex%2Aa%2B2%5Ex%2B1%E5%9C%A8x%E5%B1%9E%E4%BA%8E%EF%BC%88-%E6%97%A0%E7%A9%B7%E5%A4%A7%2C1%E3%80%91%E4%B8%8Ay%3E0%E6%81%92%E6%88%90%E7%AB%8B%2C%E6%B1%82a%E7%9A%84%E8%8C%83%E5%9B%B4)
使函数y=4^x*a+2^x+1在x属于(-无穷大,1】上y>0恒成立,求a的范围
使函数y=4^x*a+2^x+1在x属于(-无穷大,1】上y>0恒成立,求a的范围
使函数y=4^x*a+2^x+1在x属于(-无穷大,1】上y>0恒成立,求a的范围
令t= 2^x ,因为 x0 ,a>-3/4
所以-3/40也即 4a+2+1>0 ,a>-3/4
所以a>0
综上 a>-3/4