x2 + 8x −;9=?x2 + 15x + 56 =?x2 −;18x + 81 = 0 x1=?x2=?

x2 + 8x −;9=?x2 + 15x + 56 =?x2 −;18x + 81 = 0 x1=?x2=?


x^2+8x-9=(x-1)(x+9)
x1=1.,x2=-9
x^2+15x+56=(x+7)(x+8)
x1=-7,x2=-8
x^2-18x+81=(x-9)^2
x1=x2=9



√(36-x2)—5=√(25-x2)


36-x^2>=0
-6



已知橢圓E:X2、25+Y2/36=1點P(X,Y)是橢圓E上的一點,求①X2+Y2最值②求X+Y的最值


x=5cos t y=6sin t
①X^2+Y^2=25cos^t+36sin^t=25+11sin^t
∵0