Question
the length of a photograph is 1 cm less than twice the width. the area is 28 cm squared. find the dimensions of the photograph.
Answers
So the formula for the area of this photograph would be the following:
area = length x width
(let's fill in what we know from the question into this formula)
28 =(2w-1) * w
(Now let's use the distribution rule and multiply everything in the brackets by 'w')
28 = 2w^2-w
(Now let's set this equation to zero)
0=2w^2-w-28
(If you noticed, this equation in the form of y=ax^2+bx+c)
Now at this point you could use the quadratic question to solve for 'w'.
What I got for my values were -3.5 and 4
Since -3.5 does not make sense realistically, you would go with 4 cm.
Let's plug this back into the question to see if we're correct:
28 =(2w-1) * w
28= (2[4]-1)*4
28 = (8-1)*4
28 = 7*4
28 = 28
Therefore the width is 4 cm and length is 7 cm
area = length x width
(let's fill in what we know from the question into this formula)
28 =(2w-1) * w
(Now let's use the distribution rule and multiply everything in the brackets by 'w')
28 = 2w^2-w
(Now let's set this equation to zero)
0=2w^2-w-28
(If you noticed, this equation in the form of y=ax^2+bx+c)
Now at this point you could use the quadratic question to solve for 'w'.
What I got for my values were -3.5 and 4
Since -3.5 does not make sense realistically, you would go with 4 cm.
Let's plug this back into the question to see if we're correct:
28 =(2w-1) * w
28= (2[4]-1)*4
28 = (8-1)*4
28 = 7*4
28 = 28
Therefore the width is 4 cm and length is 7 cm