56x-14y(7x+9x)= 87
(-3)(5)(-2)
2xy+5xy+ -xy
0.1*pi/ln2
a+b+c=0 prove that $a^{3}$+$b^{3}$+ $c^{3}$-3abc =0
-6x + 5y = 1
6x+4y= 10
if a+b+c=0 prove that a $a^{3}$+$b^{3}$+ $c^{3}$-3abc =0
0,1*pi/ln2
6x4y= 10
6x $\sqrt{\Box}$ - 4y = 10
