\frac { 5 } { 6 } + \frac { 0,75 - 0,25 r ^ { 2 } } { 3 } = \frac { r } { 2 } - \frac { ( 5 + r ) ^ { 2 } } { 12 }
Solve for r
r=-9,5
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10+4\left(0,75-0,25r^{2}\right)=6r-\left(5+r\right)^{2}
Multiply both sides of the equation by 12, the least common multiple of 6;3;2;12.
10+3-r^{2}=6r-\left(5+r\right)^{2}
Use the distributive property to multiply 4 by 0,75-0,25r^{2}.
13-r^{2}=6r-\left(5+r\right)^{2}
Add 10 and 3 to get 13.
13-r^{2}=6r-\left(25+10r+r^{2}\right)
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(5+r\right)^{2}.
13-r^{2}=6r-25-10r-r^{2}
To find the opposite of 25+10r+r^{2}, find the opposite of each term.
13-r^{2}=-4r-25-r^{2}
Combine 6r and -10r to get -4r.
13-r^{2}+4r=-25-r^{2}
Add 4r to both sides.
13-r^{2}+4r+r^{2}=-25
Add r^{2} to both sides.
13+4r=-25
Combine -r^{2} and r^{2} to get 0.
4r=-25-13
Subtract 13 from both sides.
4r=-38
Subtract 13 from -25 to get -38.
r=\frac{-38}{4}
Divide both sides by 4.
r=-\frac{19}{2}
Reduce the fraction \frac{-38}{4} to lowest terms by extracting and canceling out 2.
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