Ta có: \(VT=\sqrt{3x^2+6x+7}+\sqrt{5x^2+10x+21}\)
\(=\sqrt{3x^2+6x+3+4}+\sqrt{5x^2+10x+5+16}\)
\(=\sqrt{3\left(x+1\right)^2+4}+\sqrt{5\left(x+1\right)^2+16}\ge2+4=6\)
Ta có: \(VP=5-x^2-2x\)
\(=-\left(x^2+2x+1\right)+6\)
\(=-\left(x+1\right)^2+6\le6\)
VP=VT khi x+1=0
hay x=-1
Vậy: x=-1
\(\sqrt{3x^2+6x+7}+\sqrt{5x^2+10x+14}=4-2x-x^2\)
\(\sqrt{3x^2+6x+7}+\sqrt{5x^2+10x+14}=4-2x-x^2\)
giải các phương trình
1) \(\sqrt{4x-20}\) +3\(\sqrt{\dfrac{x-5}{9}}\) \(-\dfrac{1}{3}\sqrt{9x-45}=6\)
2)\(\sqrt{x+1}+\sqrt{x+6}=5\)
3) \(x^2-6x+\sqrt{x^2-6x+7}=5\)
4)\(\sqrt{x+3-4\sqrt{x-1}}+\sqrt{x+8-6\sqrt{x-1}}=4\)
5)\(\sqrt{x^2-\dfrac{1}{4}+\sqrt{x^2+x+\dfrac{1}{4}}}=\dfrac{1}{2}\left(2x^3+x^2+2x+1\right)\)
6)\(\sqrt{3x^2+6x+12}+\sqrt{5x^4-10x^2+30}=8\)
7)\(\sqrt{3x^2+6x+7}+\sqrt{5x^2+10x+14}=4-2x-x^2\)
Tìm điều kiện xác định
\(A=\sqrt{x^2-5x+6}\)
\(B=\dfrac{x}{\sqrt{7x^2-8}}\)
\(C=\sqrt{-9x^2+6x-1}-\dfrac{1}{\sqrt{x^2+x+2}}\)
\(D=\sqrt{3-x^2}-\sqrt{\dfrac{2021}{3x+2}}\)
\(E=\sqrt{\dfrac{3x^2}{2x+1}-1}\)
\(F=\sqrt{25x^2-10x+1}+\dfrac{1}{1-5x}\)
bài 1
a, \(\sqrt{3x^2+6x+7}+\sqrt{5x^2+10x+14}=4-2x-x^2\)
b, \(\sqrt{x-2}+\sqrt{4-x}=x^2-6x+11\)
Giải phương trình:
a, \(\sqrt{x-7}+\sqrt{x-5}=2\)
b, \(\sqrt{x^2-6x+9}-3x=2\)
c, \(\sqrt{3x^2+6x+12}+\sqrt{5x^4+10x^2+9}=3-4x-2x^2\)
Giải PT:
a) \(\sqrt{x+1}-\sqrt{x-2}=1\)
b) \(x^2-\sqrt{x^2-2}=4\)
c) \(\sqrt{3x^2+6x+7}+\sqrt{5x^2+10x+14}=4-2x-x^2\)
Giải phương trình
1.\(\sqrt{x+4-4\sqrt{x}}+\sqrt{x+9-6\sqrt{x}}=1\)
2. \(\sqrt{3x^2+6x+7}+\sqrt{5x^2+10x+14}=4-2x-x^2\)
3. \(\sqrt[3]{2x+1}+\sqrt[3]{x}=1\)
4. \(\left(x^2+3x-4\right).\left(x^2+x-6\right)=24\)
a.\(\dfrac{5x^3-2x^2+2,5x-2,6}{x^2+3x-2,7}\) tại \(x=\sqrt{0,7}\)
b.\(\dfrac{2x^4-5x^3+2x^2-5x-30}{x^2+10x-15}\) tại \(x=-\sqrt{5}\)
