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
Answer: 216 kilometers
Step-by-step explanation:
You need the hypotenuse, this is the formula: h = √(a^2 + b^2)
so...
√(120^2 + 180^2)
√(14400 + 32400)
√46800
216.33
Answer:
54.5°
Step-by-step explanation:
You know that in a right triangle, the sine of an angle is given by ...
Sin = Opposite/Hypotenuse
sin(D) = EF/ED = 57/70
The inverse sine function is used to find the angle:
∠D = arcsin(57/70)
∠D ≈ 54.5°
Answer:
False
Step-by-step explanation:
You substitute 
for the second equation.
Then you have to distribute 
.
Combine like terms.
