Algebra problem collection (11..20)


problems 1..10
problems 21 to 27

11.
simplify:





12.

given x2 + y2 + xy = 9
x2 + z2 + xz = 16
y2 + z2 + yz = 25
what is xy + xz + yz = ?




13.
Calculate edge X of this square:





14.
Solve x in equation: 4x + 6x = 9x



15.

Given calculate a + b + c




16.

if then calculate



17.
Given is a curve with equation:
    x3 + y3 - x2 - y2 + 3xy = 0
Question:
    calculate the derivative (tangent) in point (0,0).


18.
Calculate the area of triangle ABC:





19.
Solve x in the next equation:



20.
In the picture below the area of three triangles is given.
Calculate the area of the colored triangle.