Question

PLEASE I NEED HELP ASAP! Determine if 9x2 - 42x + 49 can be the area of a square. If so, what would the value of x have to be if the area of the square is 64 square meters?
A = s2
Explain your reasoning

Answer 1

9x^2 - 42x + 49 is a perfect square trinomial. It factors to (3x - 7)^2
If the area is 64m^2 set this equal to the factors and solve.
(3x - 7)^2 = 64
Take the square root of both sides.
3x - 7 = + - 8
3x - 7 = 8 3x - 7 = - 8
Add 7 to both sides.
3x = 15 3x = - 1
Divide both sides by 3.
x = 5 x = -1/3
x cannot be -1/3 because it would make the length negative.
The answer is x= 5