one leg of a right triangle is 3 feet longer than the other leg. The length of the hypotenuse is 15ft. Find the length of the other two sides. x^2(x+3)^2=(15)^2
i know that 3^2 is 9= and 15^2=225
\[x ^{2} + (x+3)^{2} = 15^{2}\]
you got that part right it looks like...
now solving for x?
having troubles with that?
yes im stuck i believe im missing a step to square i did the 3 and 15
hmm the whole (x+3) is squared... that means (x+3)(x+3) .... you have to foil it...
or expand it, however your text calls it...
remember how to do that?
im trying
k I'll check it when you're done
is it 2x+9....
x*x + x*3 + 3*x +3*3
x^2+x^3+3x+9
x*3 = 3*x I just put them in that order to help you to see how the expanding goes...
so x^2 + 3x +3x +9 (or x^2 +6x +9)
Is that clear? Have you worked with quadratic equations much?
this was the first lesson my professor breezed through it
do you see how I got x^2 +6x +9 from (x+3)(x+3) ?
yes you got x^2 by mult x by x... than 3+3 last 3 times 3
|dw:1347820105571:dw|
x*x is x^2 3*x is 3x another 3*x is another 3x and 3*3 is 9
so... I hope that's settled:) now we need to add the other x^2 we had in your equation x^2 +x^2 +6x + 9 =15^2 2x^2 +6x +9 =15^2
yes that last line is where I left off and got stuck!
2X^2+6X+9=225
yes, now we have to solve for x so set it equal to zero and either factor it or use the quadratic formula..
turns out it's factorable...
(x+12)(x ___) can you determine what goes in the blank?
what times 12 multiplies to the product of 225 right???
no, we set it equal to zero... 2x^2 + 6x +9 -225 = 225 -225 = 0 so it's 2x^2 +6x -216 =0 divide through by two: x^2 +6x -108 =0 then factor: (x+12)(x ___) =0
Sorry, I typed 'divide through by zero' I meant "divide through by two" of course:)
(x-9)
good:)
so (x+12)(x-9) =0 x= ....?
-12 and...?
9
-12 and 9
yes. -12 is obviously not a useful answer here... so x=9!
it's not useful because there cannot be any negative numbers?!
yes. it's the side for a triangle we can't draw. x=9 is the side for a triangle we can draw:)
thank you
sure! be sure to put the length of both sides in your answer one side is 9 and the other side is 9+3 ... (you can verify that 9^2 +12^2 = 15^2 in order to check your work)
okay i did they said the answer was correct
great!
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