góc tức giao điểm, gọi giao điểm A(x₀;y₀) rồi xét y=y thay vào biểu thức tìm ra x, rồi tìm ra y, tìm ra góc

\(\left(x-1\right)^3-\left(x+2\right)\left(x^2-2x+4\right)+3\left(x-1\right)\left(x+1\right)\)

\(=\left(x^3-3x^2+3x-1\right)-\left(x^3+2^3\right)+3\left(x^2-1\right)\)

\(=x^3-3x^2+3x-1-x^3-8+3x^2-3\)

\(=3x-12\)

\(=3\left(x-4\right)\)

a) \(A=x^2-6x+11\)

\(\Leftrightarrow A=x^2-6x+9+2\)

\(\Leftrightarrow A=\left(x^2-2.x.3+3^2\right)+2\)

\(\Leftrightarrow A=\left(x-3\right)^2+2\)

Vậy GTNN của \(A=2\) khi \(x-3=0\Leftrightarrow x=3\)

b) \(B=2x^2+10x-1\)

\(\Leftrightarrow B=2x^2+10x+\dfrac{25}{2}-\dfrac{27}{2}\)

\(\Leftrightarrow B=\left(2x^2+10x+\dfrac{25}{2}\right)-\dfrac{27}{2}\)

\(\Leftrightarrow B=2\left(x^2+5x+\dfrac{25}{4}\right)-\dfrac{27}{2}\)

\(\Leftrightarrow B=2\left[x^2+2.x.\dfrac{5}{2}+\left(\dfrac{5}{2}\right)^2\right]-\dfrac{27}{2}\)

\(\Leftrightarrow B=2\left(x+\dfrac{5}{2}\right)^2-\dfrac{27}{2}\)

Vậy GTNN của \(B=\dfrac{-27}{2}\) khi \(x+\dfrac{5}{2}=0\Leftrightarrow x=\dfrac{-5}{2}\)

c) \(C=5x-x^2\)

\(\Leftrightarrow C=-x^2+5x-\dfrac{25}{4}+\dfrac{25}{4}\)

\(\Leftrightarrow C=-\left(x^2-5x+\dfrac{25}{4}\right)+\dfrac{25}{4}\)

\(\Leftrightarrow C=-\left[x^2-2.x.\dfrac{5}{2}+\left(\dfrac{5}{2}\right)^2\right]+\dfrac{25}{4}\)

\(\Leftrightarrow C=-\left(x-\dfrac{5}{2}\right)^2+\dfrac{25}{4}\)

Vậy GTLN của \(C=\dfrac{25}{4}\) khi \(x-\dfrac{5}{2}=0\Leftrightarrow x=\dfrac{5}{2}\)

a) \(1+2+3+4+.....+100\)

\(=\dfrac{\left(1+100\right).\left[\left(100-1\right):1+1\right]}{2}\)

\(=\dfrac{101.\left(99+1\right)}{2}\)

\(=\dfrac{101.100}{2}\)

\(=\dfrac{10100}{2}\)

\(=5050\)

b) \(1+3+5+....+151\)

\(=\dfrac{\left(1+151\right).\left[\left(151-1\right):2+1\right]}{2}\)

\(=\dfrac{152.\left(150:2+1\right)}{2}\)

\(=\dfrac{152.\left(75+1\right)}{2}\)

\(=\dfrac{152.76}{2}\)

\(=\dfrac{11552}{2}\)

\(=5776\)

c) \(2+5+8+......+101\)

\(=\dfrac{\left(2+101\right).\left[\left(101-2\right):3+1\right]}{2}\)

\(=\dfrac{103.\left(99:3+1\right)}{2}\)

\(=\dfrac{103.\left(33+1\right)}{2}\)

\(=\dfrac{103.34}{2}\)

\(=\dfrac{3502}{2}\)

\(=1751\)

chắc là 162 bn ạ

dù gì cũng ủng hộ cho mk tròn 20 với, please

\(y=f\left(x\right)=-2x+3\)

\(y=f\left(-2\right)=\left(-2\right)\left(-2\right)+3=4+3=7\)

\(y=f\left(-1\right)=\left(-2\right)\left(-1\right)+3=2+3=5\)

\(y=f\left(0\right)=-2.0+3=0+3=3\)

\(y=f\left(\dfrac{-1}{2}\right)=-2.\left(\dfrac{-1}{2}\right)+3=1+3=4\)

\(y=f\left(\dfrac{1}{2}\right)=-2\left(\dfrac{1}{2}\right)+3=-1+3=2\)

con cua

ai ủng hộ mấy li ke đi năm mới mà chán quá :(