
Tamara J. answered 02/18/13
Math Tutoring - Algebra and Calculus (all levels)
First, let's recall some properties of exponents.
•Product of like bases: when multiplying powers with the same base,
keep the common base and add the exponents.
e.g.: am · an = am+n
•Quotient of like bases: when dividing powers with the same base,
keep the common base and subtract the exponents.
e.g.: am/an = am-n
•Negative exponents: negative exponents indicate reciprocation,
with the exponent of the reciprocal becoming positive.
e.g.: a-m = 1/m ; 1/a-m = am ; (a/b)-m = a-m/b-m = bm/am
The problem in question is:
[(x-1y4z-4)(y-2z3x-5)]-1 = zr/(xsyt)
Let's first work out what's inside the brackets on the left-hand side of the equation:
(x-1y4z-4)(y-2z3x-5) = (x-1x-5)(y4y-2)(z-4z3)
= (x-1+(-5))(y4+(-2))(z-4+3)
= (x-6)(y2)(z-1)
=(x-6y2z-1)
Replace what is inside the brackets in the original equation by the above simplified term this simplified term:
[(x-1y4z-4)(y-2z3x-5)]-1 = zr/(xsyt)
[(x-6y2z-1)]-1 = zr/(xsyt)
Taking the reciprocal of the left-hand side of the equation, its negative exponent becomes positive:
[(x-6y2z-1)]-1 = [(x-6y2z-1)-1]/1
= 1/(x-6y2z-1)1
= 1/(x-6y2z-1)
= (1/x-6)(1/y2)(1/z-1)
Take the reciprocal of the terms with the negative exponents:
= (x6)(1/y2)(z1)
= (x6z)/y2
Replacing the left hand side of the original equation with the term above, we get:
(x6z)/y2 = zr/(xsyt)
Now we cross-multiply to arrive at the following:
(x6z)(xsyt) = y2zr
Multiply terms with like bases:
(x6xs)(yt)(z) = y2zr
(x6+s)(yt)(z) = y2zr
Dividing both sides of this equation by y2zr, we get:
[(x6+s)(yt)(z)]/(y2zr) = (y2zr)/(y2zr)
Divide the terms with like bases using the quotient of like bases property to get:
(x6+s)(yt/y2)(z/zr) = 1
(x6+s)(yt-2)(z1-r) = 1