题目

Memory（记忆） is very important. It helps you remember who you are, where you live, what you have learnt and what you plan to do in the future. So, how can you improve your memory?Memory has close relationship with the brain（大脑）. It is important to exercise your brain. For example, you can do new things. If you walk a different way to school or take a different bus, you will keep your brain active. You can try to remember something new. You can try to learn new skills. You can also study a foreign language. Your brain gets lost of regular exercise if you do any of these things.If 已知函数f（x）=ax3+bx2的图象经过点M（1，4），曲线在点M处的切线恰好与直线x+9y=0垂直．（1）求实数a，b的值；（2）若函数f（x）在区间[m，m+1]上单调递增，求m的取值范围．