Tuesday
December 10, 2013

# Posts by Mgraph

Total # Posts: 317

Math
Substitute: x^2=z => x^4=z^2 z^2-91z-900=0 (z-100)(z+9)=0 If z=100, x^2=100 then x=10 or x=-10 If z=-9, x^2=-9=9i^2 then x=3i or x=-3i

algebra
1)+-1 2),3)+-1,+-5

geometry help
115=height*(4+19)/2

Math
y=x^4-10x^2+7x+30 or y=7x+21 or ...

Statistics
a)k=1-(0.07+0.20+0.38+0.13)=0.22 b)M(X)=0*0.07+1*0.20+2*0.38+3*0.22+4*0.13= =2.14 c)M(X^2)=0*0.07+1*0.20+4*0.38+9*0.22+ +16*0.13=5.78 The standard deviation= =sqrt(M(X^2)-M(X)^2)=1.10

Algebra
Solve the equation: 11200=10000(1+0.048*(how long))

Math
Surface Area=Base Area+Lateral Area SA=BA+LA The side of the octagon a=2*apothem*tan(45/2) BA=0.5*8a*apothem=8*apothem^2*tan(45/2) LA=4a*(slant height) slant height=sqrt(height^2+apothem^2) tan(45/2)=0.4142

Calculus
The vertices of the rectangle are points: (-x,0),(x,0),(x,12-x^2),(-x,12-x^2). The area A(x)=2x(12-x^2) A(x)=24x-2x^3 A'(x)=24-6x^2=0 => x=+-2 max A(x)=A(2)=48-16=32

Geometry
The surface area SA=Pi*r^2+Pi*r*s, s=sqrt(r^2+h^2) 500*Pi=Pi*r^2+Pi*r*sqrt(r^2+225) 500=r^2+r*sqrt(r^2+225) 500-r^2=r*sqrt(r^2+225) (500-r^2)^2=(r*sqrt(r^2+225))^2 250000-1000r^2+r^4=r^2(r^2+225) 250000=1225r^2 r^2=250000/1225

Geometry
RECTANGULAR prism with bases of a RADIUS??

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