18. s = 5r^2 + 7......making r the subject
s - 7 = 5r^2
(s - 7) / 5 = r^2...by taking the sqrt of both sides, it eliminates the ^2
( sqrt (s-7)/5) = r
19. h = ut - 1/2gt^2....u = 100, t = 1 4/5(or 9/5)...g = 6.4
h = (100)(9/5) - 1/2(6.4)(9/5^2)
h = 180 - 1/2(6.4)(3.24)
h = 180 - 3.2(3.24)
h = 180 - 10.368
h = 169.632 or 169 79/125
20. sorry..do not know this one
72 m^2 (72 meters squared)
Answer: The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable, but we can work out its value if we try!
Step-by-step explanation:
Answer: C 28.47° latitude and -7.35° longitude
Step-by-step explanation:
Answer: 49x^2=-21x-2 quadratic functions -1/7and -2/7
Step-by-step explanation:
Quadratic function:
In elementary algebra, the quadratic formula is a formula that provides the solution to a quadratic equation. There are other ways of solving a quadratic equation instead of using the quadratic formula, such as factoring, completing the square, graphing and others.
Move terms to the left side
49
=-21x-2
49
-(-21x-2) =0
Distribute
49
-(-21x-2) =0
49
+21x+2=0
Use the quadratic formula
x=(-b±√
-4ac ) / 2a
Once in standard form, identify a, b, and c from the original equation and plug them into the quadratic formula.
49
+21x+2=0
let, a=49
b=21
c=2
Replace with values in this equation
X=(-b±√
-4ac ) / 2a
Simplify
Evaluate the exponent
Multiply the numbers
Subtract the numbers
Evaluate the square root
Multiply the numbers
x=(-21±7) /98
Separate the equations
To solve for the unknown variable, separate into two equations: one with a plus and the other with a minus.Separate
x=(-21+7) /98
x=(-21-7) /98
Solve
Rearrange and isolate the variable to find each solution
x=-1/7
x=-2/7
Learn more about area here https://brainly.in/question/5597925
#SPJ9