Question

The width of the blackboard in sir red's room is 4 less than its width. The blackboard has an area of 40m²

Answer 1

Complete Question :- The width of the blackboard in sir red's room is 3m less than its length. The blackboard has an area of 40m² . find the dimensions of the blackboard ?

Solution :-

Let us assume that, length of the blackboard is x m.

Since , width of the blackboard is 3m less than its length.

So,

→ width of the blackboard = (x - 3)m.

Therefore,

→ Area of blackboard = Length * width

→ Area of blackboard = x * (x - 3) m²

Now , we also have given that, The blackboard has an area of 40m².

Hence,

→ x(x - 3) = 40

→ x² - 3x = 40

→ x² - 3x - 40 = 0

→ x² - 8x + 5x - 40 = 0

→ x(x - 8) + 5(x - 8) = 0

→ (x - 8)(x + 5) = 0

→ x = 8 or (-5) .

{ value of length in negative is not possible.}

So,

→ Length of The blackboard = x = 8m. (Ans.)

→ width of The blackboard = x - 3 = 8 - 3 = 5m. (Ans.)