Sagot :
Answer:
The actual answer is A. 2x^2 + 3x + 1 = 28; x = 3
Step-by-step explanation:
First, we get the information:
L=2x+1 W=x+1 A=28
We then get the area formula.
L * W = A
So after that, we plug the equations above into the formula, and we get this.
(2x+1) * (x+1) = 28
Solve for it.
2x+1
* x+1
2x+1
2x^2 +x
2x^2+3x+1
2x^2+3x+1=28 <--- solve now! : )
2 x^ 2 + 3 x + 1 − 2 8 = 0
2 x ^2 + 3 x − 2 7 = 0
2 x ^2 + 9 x − 6 x − 2 7 = 0 (For here, you have to add another thing)
( 2 x ^2 + 9 x ) + ( − 6 x − 2 7 ) = 0 (now do common factor, which is group them)
x( 2 x + 9 ) − 3 ( 2 x + 9 ) = 0
(2x+9)(x-3)=0 now, you have to separate the equation into two.
x-3=0 2x+9=0
x=3 x=-9/2
So, one of them is 3, just as choice A.
Answer:
The length of the model = 2x+1
The width of the model = x+1
The total surface area given = 28 unit²
so the equation forms
(x+1)(2x+1) = 28unit²
x(2x+1)+1(2x+1) = 28unit²
2x²+x+2x+1 =28 unit²
2x²+3x+1 = 28 unit²
2x²+3x = 27 unit²
2x²+3x-27 = 0
now the equation is in the form of ax²+bx+c = 0
so if a = 2 ,b = 3 and c = -27
then we know ax²+bx+c= 0
so x = -b±√b²-4ac/2a
so here x = -3±√9+216/4
x= -3±√255/4
so x₁ = -3+√255/4 = 3.24 units
and x₂ = -3-√255/4 = -4.74 units
so x{3.24,-4.74}units (ans)
Hope it helps