## anonymous one year ago I need someone to explain this to me Let u = <-5, 1>, v = <7, -4>. Find 9u - 6v.

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1. TheSmartOne

$$\bf a <b,c>~ =~ <ab,ac>$$

2. anonymous

I don't understand?

3. anonymous

@TheSmartOne

4. TheSmartOne

$$\bf y=~<a,b>$$ $$\bf z=~<c,d>$$ $$\bf y-z =$$ $$\sf <a,b> - <c,d>~= ~<a,b> -<c,d>~=~<a-c,~b-d>$$

5. anonymous

okay im even more confused

6. TheSmartOne

$$\bf y=~<a,b>$$ $$\bf z=~<c,d>$$ $$\bf y-z =$$ $$\sf <a,b> - <c,d>~=~<a-c,~b-d>$$ Oops, fixed the redundant error...

7. TheSmartOne

https://www.mathsisfun.com/algebra/vectors.html Review the topic :p

8. anonymous

could you possibly plug in the numbers for the Y & Z?

9. anonymous

Yes i need an explanation, not symbols

10. TheSmartOne

$$\bf u= ~<-5,1>$$ $$\bf 9u = 9<-5,1>~= <9\times (-5) , 9\times 1>$$

11. TheSmartOne

That's unfortunate, because we can't solve this without the vector symbol :p

12. TheSmartOne

so what is $$\sf 9\times (-5) =?$$ and $$\sf 9\times1 =?$$

13. anonymous

-45 & 9

14. TheSmartOne

correct, so now we have $$\bf 9u =~<-45,9>$$