SOLUTION: I need help solving this problem. (x+4)(x-9)=4x

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Question 273318: I need help solving this problem. (x+4)(x-9)=4x
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+%28x%2B4%29%28x-9%29=4x
x%5E2+%2B+4x+-+9x+-+36+-+4x+=+0
x%5E2+-+9x+-+36+=+0
Completing the square:
x%5E2+-+9x+%2B+%289%2F2%29%5E2+=+%289%2F2%29%5E2+%2B+36
x%5E2+-+9x+%2B+81%2F4+=+81%2F4+%2B+144%2F4
%28x+-+%289%2F2%29%29%5E2+=+225%2F4
x+-+9%2F2+=+15%2F2
x+=+12
and
x+-+9%2F2+=+-15%2F2
x+=+-3
the solutions are x+=+12 and x+=+-3
check:
+%28x%2B4%29%28x-9%29=4x
%2812%2B4%29%2812-9%29+=+4%2A12
16%2A3+=+48
48+=+48
and
%28-3%2B4%29%28-3-9%29+=+4%2A%28-3%29
1%2A%28-12%29+=+-12
-12+=+-12
OK