(1)当m=-2时,函数y=left(begin(array)l(x+2,x<2)\(-x-2,x≥-2)end(array)right.,because 点Dleft(3,nright)在图象G上,therefore x=3时,n=-5.(2)①当4-m lt m时,即m gt 2,对于函数y=x-fracm2+1.随着x的增大y也增大.therefore 当x=3-m时,函数有最小值:y_1=
left(begin(array)l3x+4z=7①\ 2x+3y+z=9②\ 5x-9y+7z=-6③end(array)right. ②times 3+③得11x+10z=21④ ④times 2-①times 5得7x=7 解得x=1 把x=1代入①得3+4z=7 解得z=1 把x=1,z=1代入②得2+3y+1=9 解得y=2 方程组的解为left(begin(array)lx=1\ y=2\ z=1...
× 解析：试题分析：先通分，再移项合并同类项即可。解：方程组(\left{ \begin{array}{l}{\frac{x+5}{2}+\frac{y+5}{3}=7} \ {\frac{x+4}{3}+\frac{2y-3}{5}=2} \end{array} \right.)整理得：(\left{ \begin{array}{l}{3x+2y=23} \ {5x+6y=19} \end{array} \right.)故答案...
解答解:由\left\{\begin{array}{l}x=-3+2cosθ\\ y=4+2sinθ\end{array}\left\{\begin{array}{l}x=-3+2cosθ\\ y=4+2sinθ\end{array},得{x+3=2cosθy−4=2sinθ{x+3=2cosθy−4=2sinθ,两式平方作和得,(x+3)2+(y-4)2=4; ...
15.函数f(x)=$\left\{\begin{array}{l}\frac{1}{x}\end{array}$的大致图象是( )A.B.C.D.
方程组left( begin(array)l(19x+18y=17①) \ (17x+16y=15②) end(array) right. ①-②,得:2x+2y=2,即x+y=1③. ②-③×16,得:x=-1. 将x=-1代入③得:y=2, ∴方程组的解为:left(begin(matrix)x=-1=2end(matrix)right.. 【考点提示】 本题主要考查的是解二元一次方程组,明确例题...
∵a*b=left(begin(array)l(a^b(a≤b,a≠0))\(b^a(a>b,b≠0))end(array)right.,(a-1)*(a-4)=1,∴(a-4)a-1=1,∴a-4=1或a-4=-1且a-1为偶数或a-1=0且a-4≠0,解得,a=5或a=3或a=1,故答案为:1或3或5.反馈 收藏 ...
解下列方程组(1)left{begin{array}{l}3u+2t=7\ 6u-2t=11end{array}right.(2)left{begin{array}{l}
分析∴当x≥0时,x(x+4)=12;当x<0时,x(x-4)=12.由此能求出结果. 解答解:∵f(x)=\left\{{\begin{array}{l}{x(x+4),x≥0}\\{x(x-4),x<0}\end{array}}\left\{{\begin{array}{l}{x(x+4),x≥0}\\{x(x-4),x<0}\end{array}},f(x)=12, ...
解答 解:作出函数f(x)=\left\{\begin{array}{l}{{x^2}-2x,x≥-1}\\{x+4,x<-1}\end{array}}\left\{\begin{array}{l}{{x^2}-2x,x≥-1}\\{x+4,x<-1}\end{array}}的图象如图, 函数y=x+4 在 x∈(-∞,-1)上单调增,其值域为(-∞,3]; ...