Question 1207407
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Looks good so far.


(3x + 13)^2 + x^2 = (4x + 5)^2
(3x + 13)(3x + 13) + x^2 = (4x + 5)(4x + 5)
9x^2+39x+39x+169 + x^2 = 16x^2+20x+20x+25
10x^2+78x+169 = 16x^2+40x+25
0 = 16x^2+40x+25-(10x^2+78x+169)
0 = 16x^2+40x+25-10x^2-78x-169
0 = 6x^2-38x-144
6x^2-38x-144 = 0


From here use the quadratic formula. 
I'll let the student finish up.
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