Tìm \(f'\left(1\right),f'\left(2\right),f'\left(3\right)\) nếu :
\(f\left(x\right)=\left(x-1\right)\left(x-2\right)^2\left(x-3\right)^3\)
Cho hàm số \(f\left(x\right)=\frac{2x+1}{x^2\left(x+1\right)^2}\).Tìm các số nguyên dương x,y sao cho:
\(S=f\left(1\right)+f\left(2\right)+f\left(3\right)+...+f\left(x\right)=\frac{2y\left(x+1\right)^3-1}{\left(x+1\right)^2}-19+x\)
\(f\left(x\right)=\frac{x^2+2x+1-x^2}{x^2\left(x+1\right)^2}=\frac{\left(x+1\right)^2-x^2}{x^2\left(x+1\right)^2}=\frac{1}{x^2}-\frac{1}{\left(x+1\right)^2}\)
\(\Rightarrow f\left(1\right)+f\left(2\right)+....+f\left(x\right)=1-\frac{1}{2^2}+\frac{1}{2^2}-....-\frac{1}{\left(x+1\right)^2}\)
\(\Rightarrow\frac{2y\left(x+1\right)^3-1}{\left(x+1\right)^2}-19+x=\frac{x\left(x+2\right)}{\left(x+1\right)^2}\)
\(\Leftrightarrow\frac{2y\left(x+1\right)^3-1}{\left(x+1\right)^2}-19+x=\frac{2y\left(x+1\right)^3-1}{\left(x+1\right)^2}-20+\left(x+1\right)=\frac{x\left(x+2\right)}{\left(x+1\right)^2}\)
Dat:\(x+1=a\Rightarrow\frac{\left(2y+1\right)a^3-20a^2-1}{a^2}=\frac{a^2-1}{a^2}\Leftrightarrow\left(2y+1\right)a^3-20a^2-1=a^2-1\)
\(\Leftrightarrow\left(2y+1\right)a^3-20a^2=a^2\Leftrightarrow\left(2ay+a\right)-20=1\left(coi:x=-1cophailanghiemko\right)\)
\(\Leftrightarrow2ay+a=21\Leftrightarrow a\left(2y+1\right)=21\Leftrightarrow\left(x+1\right)\left(2y+1\right)=21\)
Cho hàm số \(y = f\left( x \right) = - {x^2} + 1\). Tính \(f\left( { - 3} \right);f\left( { - 2} \right);f\left( { - 1} \right);f\left( 0 \right);f\left( 1 \right)\).
\(f\left( { - 3} \right) = - {\left( { - 3} \right)^2} + 1 = - 9 + 1 = - 8\);
\(f\left( { - 2} \right) = - {\left( { - 2} \right)^2} + 1 = - 4 + 1 = - 3\);
\(f\left( { - 1} \right) = - {\left( { - 1} \right)^2} + 1 = - 1 + 1 = 0\);
\(f\left( 0 \right) = - {0^2} + 1 = 0 + 1 = 1\);
\(f\left( 1 \right) = - {1^2} + 1 = - 1 + 1 = 0\);
Cho hàm số \(y = f\left( x \right) = {x^2} + 4\). Tính \(f\left( { - 3} \right);f\left( { - 2} \right);f\left( { - 1} \right);f\left( 0 \right);f\left( 1 \right)\)
\(f\left( { - 3} \right) = {\left( { - 3} \right)^2} + 4 = 9 + 4 = 13\);
\(f\left( { - 2} \right) = {\left( { - 2} \right)^2} + 4 = 4 + 4 = 8\);
\(f\left( { - 1} \right) = {\left( { - 1} \right)^2} + 4 = 1 + 4 = 5\);
\(f\left( 0 \right) = {0^2} + 4 = 0 + 4 = 4\);
\(f\left( 1 \right) = {1^2} + 4 = 1 + 4 = 5\).
Cho hàm số \(y=f\left(x\right)=\frac{2}{3}x\)
Tính \(f\left(-2\right);f\left(-1\right);f\left(0\right);f\left(\frac{1}{2}\right);f\left(1\right);f\left(2\right);f\left(3\right)\)
Cho các hàm số \(f\left(x\right)=x^2+2+\sqrt{2-x};g\left(x\right)=-2x^3-3x+5\)
\(u\left(x\right)=\left\{{}\begin{matrix}\sqrt{3-x};\left(x< 2\right)\\\sqrt{x^2-4};\left(x\ge2\right)\end{matrix}\right.\)
\(v\left(x\right)=\left\{{}\begin{matrix}\sqrt{6-x};\left(x\le0\right)\\x^2+1;\left(x>0\right)\end{matrix}\right.\)
Tính các giá trị \(f\left(-2\right)-f\left(1\right);f\left(-7\right)-g\left(-7\right);f\left(-1\right)-u\left(-1\right);u\left(3\right)-v\left(3;\right)v\left(0\right)-g\left(0\right);\dfrac{f\left(2\right)-f\left(-2\right)}{v\left(2\right)-v\left(-3\right)}\) ?
\(f\left(-2\right)-f\left(1\right)=\left(-2\right)^2+2+\sqrt{2-\left(-2\right)}-\left(1^2+2+\sqrt{2-1}\right)\) \(=8-4=4\).
\(f\left(-7\right)-g\left(-7\right)=\left(-7\right)^2+2+\sqrt{2-\left(-7\right)}-\left(-2.\left(-7\right)^3-3.\left(-7\right)+5\right)=-658\)
Tìm hàm f: \(R\rightarrow R\) thỏa mãn điều kiện
1. \(f\left(x^2+f\left(y\right)\right)=y+x.f\left(x\right),\forall x,y\in R\)
2. \(f\left(\left(x+1\right).f\left(y\right)\right)=f\left(y\right)+y.f\left(x\right),\forall x,y\in R\)
3. \(f\left(x^3+f\left(y\right)\right)=x^2f\left(x\right)+y,\forall x,y\in R\)
4. \(\hept{\begin{cases}f\left(x+y\right)=f\left(x\right)+f\left(y\right)\\f\left(xy\right)=f\left(x\right).f\left(y\right)\end{cases}},\forall x,y\in R\)
@Lê Minh Đức
@alibaba nguyễn : Giúp với ông ei :) Chắc ông cũng học đến cái này r :))
cho hàm số \(f\left(x\right)=\dfrac{\left(sinx+2x\right)\left[\left(x^2+1\right)sinx-x\left(cosx+2\right)\right]}{\left(cosx+2\right)^2\sqrt{\left(x^2+1\right)^3}}\). Biết F(x) là một nguyên hàm của f(x) và F(0)=2021. Tính giá trị biểu thức T=F(-1) + F(1).
Cho \(f\left(x\right)=\left(x^2+x+1\right)^2+1\).Gọi n là số nguyên dương nhỏ nhất mà \(\frac{f\left(2\right).f\left(4\right)......f\left(2n\right)}{f\left(1\right).f\left(3\right).....f\left(2n-1\right)}>2^{2013}\)
Tìm chữ số tận cùng của n
f:\(R^+\rightarrow R^+\) thỏa f(1)=\(\dfrac{1}{2}\) và f(x.y)=\(f\left(x\right)\).\(f\left(\dfrac{3}{y}\right)\) +\(f\left(y\right)\).\(f\left(\dfrac{3}{x}\right)\) \(\forall x,y\in R^+\) .Tìm f