Perform the indicated operations and reduce the answer.
1 answer:
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Answer:
x² = 81 , x = ± 9
x² - 18x = 7 : x = 9 ± √(22)
Step-by-step explanation:
x² = 81
simply take the square root of both sides
x = ± 9
x² - 18x = 7
This question is a bit more complicated as there is a variable with a power as well as a variable with no power. To solve for x we are going to have to put the equation in quadratic form then solve using the quadratic equation
x² - 18x = 7
put the equation in quadratic form by subtracting 7 from both sides so that the equation is equal to 0
x² - 18x - 7 = 0
we can now solve for x using the quadratic equation
recall the quadratic equation :
where the value of a,b and c are derived from the equation
remember the equation is in quadratic form ax² + bx + c = 0
so ax² + bx + c = 0 : x² - 18x - 7 = 0
knowing this we can assign variables, a = 1 , b = -18 and c = -7
now we plug in the variables into the quadratic equation
recall equation :
a = 1 , b = -18 and c = -7
plug in values
remove parenthesis
simplify exponent
simplify multiplication in square root and on denominator
simplify addition
simplify radical
simplify fraction
and we are done!