What is the value of $a + b + s + t$

Question

I'm confused as to how to approach this. I've tried to foil it out.

$$x^3(3x-1)=a+bx+sx^2+tx^3$$ The equation above is true for all values of $x$, where $a$, $b$, $s$, and $t$ are constants. What is the value of $a+b+s+t$?

score 5 · Answer 1 · answered Mar 14 '15 at 03:19

5

hint: let $x = 1$ in the equation.

answered Mar 14 '15 at 03:19

DeepSea

77,651

holy crap im an idiot. thank you @BRICKS-Fan – Hamza Mar 14 '15 at 03:21
1

Without the insight, one could note that $x^2(3x-1)=3x^3-x^2$. – André Nicolas Mar 14 '15 at 03:23
... or even note that the $x^2$ multiplier isn't going to change the result... – Joffan Mar 14 '15 at 03:27

What is the value of $a + b + s + t$

1 Answers1