Question

(x+5)square-(x-8)square=26.5

Answer 1

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$(x + 5) {}^{2} - (x - 8) {}^{2} = 26.5 \\ x {}^{2} + 25 + 10x - (x {}^{2} + 64 - 16x) = 26.5 \\ x {}^{2} + 10x + 25 - x {}^{2} - 64 + 16x = 26.5 \\ 10x + 16x = 26.5 - 25 + 64 \\ 26x = 65.5 \\ x = \frac{65.5}{26} \\ x = 2.519 \\ x = 2.52$


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Answer 2

(x+5)^2 - (x-8)^2 =26.5

by the formula
a^2-b^2 =(a+b) (a-b)

(x+5 +x-8) (x+5 -x+8) = 26.5

(2x-3)(13) =26.5
2x-3 = 26.5/13
2x = (26.5 /13 ) +3
2x = 2.038 +3
2x = 5.038
x = 5.038/2
= 2.519
hence x= 2.519