contestada

a cuboid with a volume of 924cm3 has dimensions
4cm , (x+1)cm,( x+11)cm
show clearly that x2+112x-220=0
solve the equation by factorisation, making sure you show the factorisation
state both values of x
finally , find the dimension of the cuboid

Respuesta :

Answer:

4cm, 11cm, and 21cm

Step-by-step explanation:

The given dimensions of the cuboid are:

4cm , (x+1)cm,( x+11)cm

The volume of the cuboid is given as 904cm³

We know volume of a cuboid is given as:

V=LBH

We substitute the dimensions to get:

[tex]4(x + 1)(x + 11) = 924[/tex]

Divide through by 4.

[tex](x + 1)(x + 11) = 231[/tex]

We expand on the left to get:

[tex] {x}^{2} + 11x + x + 11 = 231[/tex]

[tex] {x}^{2} + 12x + 11 - 231= 0[/tex]

This simplifies to:

[tex] {x}^{2} + 12x - 220= 0[/tex]

To factor this expression we obtain:

[tex] {x}^{2} + 22x - 10x - 220 = 0[/tex]

[tex] {x}(x + 22) - 10(x + 22) = 0[/tex]

[tex](x + 22)(x - 10) = 0[/tex]

[tex]x = 10 \: or \: - 22[/tex]

But the dimension must be positive:

hence x=10

Therefore the dimensions are 4cm, 11cm, and 21cm