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5r-7(1+r)=5
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2 Answers
5r-7(1+r)=5
First solve for the -7(1+r) = -7-7r, then plug back into equation -
5r-7-7r= 5
5r-7r = 5+ 7 (when -7 goes over to the other side, the - sign changes to +)
-2r=12
r=-6
To check -
5r-7(1+r) , where r = -6
5(-6) -7(1+(-6))
-30 -7(-5) ---> multiply first
-30 +35 = 5
Therefore, r = -6
5r - 7 - 7r = 5
-2r - 7 = 5
-2r = 12
r = -6
Comments
by multiplying the -7 through the (1+r), so -7 x 1 = -7 and -7 x (r) = -7r
therefore -7(1+r) = -7-7r
- Timothy W. 12/5/2012Further on in the problem... Remember that what you do to one side of the equation you must do to the other to keep them equal. So...
-2r - 7 + 7 = 5 + 7 =>> -2r = 12
See how we added 7 to both sides so that only the varialbles are on one side while the numbers are on the other side? This allows us to divide by the co-efficient ( -2 in -2r) and get the resulting r = -6.
- Timothy W. 12/5/2012thx bigg help i got stuck cuz i 4got i had 2 use -7 instead of +7 wen u do the distributive property
Comments
You very welcome. Here is rule of thumb, I call it BODMAS
B = Brackets "()"
O = Off which denote "="
D = Division "/"
M = Multiply "x"
A = Addition "+"
S = Subtract "-"
These must follow in order, in other words, for every equation, the bracket columns must be solved first or expanded. In your equation, solved the brackets first, then further down the order. Also, keep in mind of these
(-) *(-) = + (+)*(+) = +
(-)*(+) = - (+)*(-)= -
If you follow these simple rules, you'll be able to solve most algebraic equations easily.
- Emmanuel U. 12/5/2012