Question

A cuboid with a volume of 924 cm' has dimensions

4 cm, (x + 1) cm and (x + 11) cm.
Show clearly that x2 + 12x – 220 = 0
Solve the equation by factorisation, making sure you show the factorisation.
State both values of x on the same line.
Finally, find the dimensions of the cuboid, writing all three on one line.

Answer 1

Dimensions = 4cm, 11cm and 21 cm.

Explanation:

x2 + 12x - 220 = 0

x2 + 22x - 10x - 220

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

=(x+22)(x-10)

x + 22= 0

-22 -22

x = -22 (x cant be negative so this is wrong)

x-10 = 0

+10 +10

x = 10 (positive so its correct)

4 , (10+1), (10+11)

= 4, 11, 21 cm.

Answer 2

4cm, 11cm, 21cm

Explanation:

4(x + 1)(x + 11)

4(x ^ 2 + 12x + 44)

x ^ 2 + 12x + 11 = 231

x ^ 2 + 12x + 11 - 231 = 0

x ^ 2 + 12x - 220 = 0

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

x = 10 and x = - 22

4cm , 11cm , 21cm

Hope it helps you xx