How do you solve −u7=512+u?

1 Answer
demathgirl
Jun 11, 2017

u = -7 or -5

Explanation:

−u7=512+u ?

I would move the negative sign to the seven

u−7=512+u

Then cross multiply

u(12+u)=−7(5)

Solve

12u+u2=−35

Move to the -35 to the other side of the question by adding to both sides. This will make one side zero. I would then put the equation into standard form.

u2+12u+35=0

Factor it. (if you want to see more details about how to do this step, please leave a comment and i'll be glad to go into more detail.

(u+7)((u+5)=0

So in order to get the product (the answer of a multiplication problem) to be zero. One of the two terms must be equal to zero. that means

u+7=0 or u+5=0

Solve each equal separately
u+7−(7)=0−(7)→u=−7
u+5−(5)=0−(5)→u=−5

so u = -7 or -5

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