Answer: x = 4
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Work Shown:
As you mentioned, we'll use Pythagoras' Theorem aka Pythagorean Theorem.
![a^2+b^2 = c^2\\\\(x+3)^2+(4(x+2))^2 = 25^2\\\\(x+3)^2+16(x+2)^2 = 625\\\\(x^2+6x+9)+16(x^2+4x+4) = 625\\\\x^2+6x+9+16x^2+64x+64 = 625\\\\17x^2+70x+73 = 625\\\\17x^2+70x+73-625 = 0\\\\17x^2+70x-552 = 0\\\\](https://img.qammunity.org/2023/formulas/mathematics/high-school/np748x3173d44imru1i3d4pzmjg28tryk2.png)
Next, we'll use the quadratic formula with a = 17, b = 70, c = -552.
![x = (-b\pm√(b^2-4ac))/(2a)\\\\x = (-70\pm√((70)^2-4(17)(-552)))/(2(17))\\\\x = (-70\pm√(42436))/(34)\\\\x = (-70\pm206)/(34)\\\\x = (-70+206)/(34) \ \text{ or } \ x = (-70-206)/(34)\\\\x = (136)/(34) \ \text{ or } \ x = (-276)/(34)\\\\x = 4 \ \text{ or } \ x \approx -8.1176\\\\](https://img.qammunity.org/2023/formulas/mathematics/high-school/hiy6i8xbrjszabna4un9d4d2z0f5udelar.png)
Ignore the negative x value solution. The sides (x+3) and 4(x+2) will be negative values if we plugged in x = -8.1176, but negative side lengths do not make sense.
This makes x = 4 the only possible solution.
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If x = 4, then,
- vertical leg = x+3 = 4+3 = 7
- horizontal leg = 4(x+2) = 4*(4+2) = 4*6 = 24
This is a 7-24-25 right triangle.
We can confirm this using the pythagorean theorem
![a^2+b^2 = c^2\\\\7^2+24^2 = 25^2\\\\49+576 = 625\\\\625 = 625 \ \ \ \checkmark](https://img.qammunity.org/2023/formulas/mathematics/high-school/kvhb70j614dc7de76kejvvncjsfx8658k1.png)