Question

16. A rectangle of length (4x - 1) cm and breath 2xcm has an area of 10cm2. Find

Answer 1

A) 2x(4x-1)=10

Expand

8x^2-2x=10

Divide all terms by 2

4x^2-x=5

4x^2-x-5=0

4x^2+4x-5x-5=0

4x(x+1)-5(x+1)=0

(4x-5)(x+1)=0

x is equal to -1 and 5/4

but, in this case, the side of a rectangle cannot be negative, so the only answer that is mathematically possible is 5/4

b) substitute 5/4 into given expressions

length: 4(5/4)-1 which is 4cm

width: 2*5/4 which is 2.5cm

c) plus all four sides together

2.5+2.5+4+4 which is 13cm