Question

A cuboid with a volume of 924cm^3 has dimensions 4cm, (x+1)cm and (x+11). Show clearly that x^2+12x-220=0 solve the equation by factorisation, making sure you show the factorisation. Finally, find the dimensions of the cuboid,

Answer 1

Answer:

$x^2+12x-220=0$ -- Proved

$x = 10\ \ \ x = -22$

Step-by-step explanation:

Given

$Volume = 924cm^3$

$Dimension: 4cm; (x+1)cm; (x+11)cm$

Required

Show that $x^2+12x-220=0$

The volume is calculated as:

$4 * (x + 1) * (x + 11) = 924$

Open the brackets

$(4x + 4) * (x + 11) = 924$

$4x^2 + 44x + 4x + 44 = 924$

$4x^2 + 48x+ 44 = 924$

Collect Like Terms

$4x^2 + 48x+ 44 - 924=0$

$4x^2 + 48x -880=0$

Divide through by 4

$\frac{4x^2}{4} + \frac{48x}{4} -\frac{880}{4}=0$

$x^2+12x-220=0$

Solving further:

Expand the expression

$x^2 + 22x - 10x - 220 = 0$

Factorize:

$x(x + 22) - 10(x + 22) = 0$

$(x - 10)(x + 22) = 0$

Split:

$x - 10 = 0;\ \ \ x + 22 = 0$

$x = 10\ \ \ x = -22$