The third choice, 4x²+18x+0.25=0, is correct.
The frame will have the same thickness on both sides of the mirror. Therefore we add 5+x+x to get the total length, and we have 4+x+x to get the total width.
The area is found by multiplying the total width and total length:
A=(5+x+x)(4+x+x)
A=(5+2x)(4+2x)
Multiplying the binomials, we have:
A=5*4+5*2x+2x*4+2x*2x
A=20+10x+8x+4x²
A=20+18x+4x²
We know that the area is 19.75:
19.75=20+18x+4x²
We need quadratics set equal to 0, so subtract 19.75 from each side:
19.75-19.75 = 20+18x+4x²-19.75
0=0.25+18x+4x²
In standard form, it will be:
4x²+18x+0.25=0
-4x-11. Plug -15 in for x into the equation. -4(-15)-11. That gives you 49. Therefore, making choice C correct.
Hey there! :D
The biggest thing to remember here is the similar triangles and their side lengths.
Okay, so we can separate these triangles into 3 similar triangles. Which, we only need to do that to two for a proportion, but if you were to have more variables, you could separate the triangles even more if you needed to.
We want to find two triangles that have "x" has a value of their side, so we can solve a proportion.
The bigger triangle, (the whole two triangles combine) and the smaller triangle on the left can be used to make a proportion.
On the smaller triangle:
We have 9 cm on the shorter side and x as the hypotenuse.
On the larger triangle:
We have x as the shorter side, and then 25 as the hypotenuse. (9+16)
Note: You have to flip the larger triangle upside down to make it a similar structure to the other two triangles. It is similar, you just have to flip it.
So, now we can make a proportion.

Now, cross multiply.
9*25= 225
x*x=

So, find the square root.
√225= 15
x= 15. I hope this helps!
~kaikers
The volume of a cylinder is r^2

dh
enter values, then you get 3.53, multiply that by the BTU, the answer is 8888 BTU
Answer:
Divide each term by 5, looking at the coefficients. The answer is x - 7y + 10
Step-by-step explanation: