Dangerous UV waves, and long radio waves
7 % of cost price is 2.80 , What about 1%?
7 = 2.80
1 = x (where x is the price value of 1% in dollars)
We simplify the above equation, so:
7 × x = 2.8 × 1 → 7x = 2.8 → x = 2.8 / 7 → x = 0.4 dollars
We know that 100% represents the whole price,
so if 1% is 0.4 dollars, then 100% will be 0.4 × 100 = 40 dollars
Therefore the store charged $40 dollars for the helmet before tax
Answer:
(x + 4)² + (y + 7)² = 4
Step-by-step explanation:
Surface area of box=1200 cm²
<span>Volume of box=s²h </span>
<span>s = side of square base </span>
<span>h = height of box </span>
<span>S.A. = s² + 4sh </span>
<span>S.A. = surface area or 1200 cm², s²
= the square base, and 4sh = the four 'walls' of the box. </span>
<span>1200 = s² + 4sh </span>
<span>1200 - s² = 4sh </span>
<span>(1200 - s²)/(4s) = h </span>
<span>v(s) = s²((1200 - s²)/(4s)) </span>
<span>v(s) = s(1200 - s²)/4 . </span>
<span>v(s) = 300s - (1/4)s^3</span>
by derivating
<span>v'(s) = 300 - (3/4)s² </span>
<span>0 = 300 - (3/4)s² </span>
<span>-300 = (-3/4)s² </span>
<span>400 = s² </span>
<span>s = -20 and 20. </span>
again derivating
<span>v"(s) = -(3/2)s </span>
<span>v"(-20) = -(3/2)(-20) </span>
<span>v"(-20) = 30 </span>
<span>v"(20) = -(3/2)(20) </span>
<span>v"(20) = -30 </span>
<span>v(s) = 300s - (1/4)s^3 </span>
<span>v(s) = 300(20) - (1/4)(20)^3 </span>
<span>v(s) = 6000 - (1/4)(8000) </span>
<span>v = 6000 - 2000
v=4000</span>
3x + 4y = 16
-4x - 3y = -19
4( 3x + 4y = 16)
3( -4x - 3y = -19)
Distribute
12x + 16y = 64
-12x - 9y = -57
Now subtract both equations
7y = 7
/7 on both sides
y = 1
Substitute y = 1 in one of the equations.
3x + 4y = 16
3x + 4(1) = 16
-4 on both sides
3x = 12
/3 on both sides
x = 4
Answer:
x = 4
y = 1
