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# Solve for r.......................?

r^2+3r=2

### 3 Answers

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- Mr. BrightsideLv 51 decade agoFavorite Answer
this can be written as

r^2 + 3r - 2 = 0

Now to solve this you can use the discriminat method (delta = b^2 - 4ac....)

But if you still haven't learnt this method, then use the method of completing the square.

r^2 + 3r + (3/2)^2 - (3.2)^2 -2 =0

(r + 3/2)^2 = 9/4 + 2 = 17/4

r+3/2 = +or- sqrt(17/4)

r = + sqrt(17/4) - 3/2

or r = - sqrt(17/4) - 3/2

PS: this is actually a particular derivation of the discriminant method)

- ComoLv 71 decade ago
r ² + 3r - 2 = 0

x = [ - b ± √ ( b ² - 4 a c ) ] / 2 a

x = [ - 3 ± √ ( 9 + 8 ) ] / 2

x = [ - 3 ± √ ( 17 ) ] / 2

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