5X2+4=?

4x2.5x2+4x2×2+2x2.5x2= 5X2+4=? √(x2-25/4)+√(x2-9/4)=5 求值域:y=(x2+5)/根号(x2+4) 求y=x2+5/根号x2+4的最小值 2/5x2/4=? 解分式方程:2/x2+5x+6 + 3/x2+x-6=4/x2-4 已知x2-5x+=0,求x2-4x2-1 1/(x2+x)+1/(x2+3x+2)+1/(x2+5x+6)+1/(x2+7x+12)=4/21x2是x的平方 mathematica如何求解含有三角函数的方程?FindRoot[{3 x1^3 + 2 x2 - 5 + Sin[x1 - x2] Sin[x1 + x2] == 0,-x1*Exp[x1 - x2] + x2 (4 + 3 x2^2) + 2 x3 + Sin[x2 - x3] Sin[x2 + x3] - 8 == 0,-x2*Exp[x2 - x3] + 4 x3 - 3 ==0},{x1,Pi/2},{x2,2},{x3,0}] 15X2/5X2/5X2/5= 4x2-3y2+2xy-4x2+5x2 x2-5x+1=0则x2+x2/1 2+5x2+5x2=? 不等式(x2-4x-5)(x2-8) (1-x2)(x2-4x+5) 不等式（x2-4x-5)(x2+1) 3x2.5x2 =多少?