How to calculate the perimeter of a rectangle if the area is 42 and the legth is one more than the width?

Let us assume that the length of the rectangle is L and
the width is W.

Given that the area is
42.

But wer know that the area 
L*W

==> L*W = 42
...............(1)

Now we are given the L is one more than
W.

==> L =
W+1.............(2)

We will substitute (2) into
(1).

==> (W+1) * W =
42

==> w^2 + w =
42

==> w^2 + w - 42 =
0

We will factor.

==>
(W+7) ( w-6) = 0

==> w1= -7 ( not
valid)

==> w2= 6 ==> L = 6+1 =
7

Then we have L =7 and W= 6, we will calculate the
perimeter.

==> We know that P = 2L + 2W = 2*7 + 2*6
= 14+12 = 26

Then the perimeter of the
rectangle is 26 units.