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question:What digits should be written in place of each letter (different letters represent different digits) to make the following two additions correct: [ A B C ] [ | D E F | ] [ | quad + G E | ] [ mathrm{G} E F ] [ | quad + mathrm{D} E | ] [ mathrm{H} F J | ]
answer:Let us analyze the given system of equations: ``` A B C + D E F + G E ------- G E F G E F + D E ------- H F J ``` Our goal is to determine the digits represented by the letters ( A, B, C, D, E, F, G, H, ) and ( J ). 1. **Determining ( C )**: - The first simplification we can make is observing the last digit in each row of the addition: [ C + F + E = F ] - This implies ( C = 0 ), because only then can ( C + F + E = F ) hold true (adding zero retains the digit on the right-hand side). 2. **Find conditions for ( F ) and ( E )**: - Observing the next column, from the right: [ B + E + E = E + 10 ] - Therefore, ( B + E = 10 ). 3. **Considering the second equation**: - Working on the addition: [ 2F text{ is greater than or equal to } 10 ] - Consequently, ( F + F = 10 + (carry) ). We realize that ( E ) contributes to the carry-over, and ( F = E + 1 ). 4. **Exploring possible values of ( F )**: - ( F neq 9 ), as it would force ( E ) to be ( 8 ), making ( J geq 16 ) (which is not a valid digit). - ( F neq 6 ), as it would force ( E ) to be ( 5 ), and ( B = 5 ) leading to duplication. - ( F neq 7 ), as it would force ( E ) to be ( 6 ), making ( B = 4 ) and ( J = 14 ). 5. **Assigning Values**: - ( F = 8 ), ( E = 7 ), then ( B = 3 ) as ( B + 7 = 10 ). - Combining all this: [ H = 5 text{ (as } B + E + E + 2D + A)leq 2H. ] - Solving ( A + 2D + 1 = H = 5 ), we compute: [ A + 2D + 1 = 5 ] - Assign values: ( A = 2 ), ( D = 1 ), and hence ( G = 4 ). 6. **Completing the Solution**: - Revalidate each step and digit substitution to check the consistency of assignments in the original equation setup. # Conclusion This analysis successfully assigns each letter a unique digit satisfying the constraints: [ A = 2, B = 3, C = 0, D = 1, E = 7, F = 8, G = 4, H = 5, J = 6 ] Thus, the correct digit mapping is confirmed to be: [ boxed{A=2, B=3, C=0, D=1, E=7, F=8, G=4, H=5, J=6} ]
question:Compute the sum of all the roots of (2x+3)(x6) + (2x+3)(x8) = 0.
answer:The given expression can be rearranged and factored by taking out the common factor: [ (2x+3)(x-6) + (2x+3)(x-8) = (2x+3)((x-6) + (x-8)) ] [ = (2x+3)(2x - 14) = 2(2x+3)(x-7) ] This simplifies to: [ 2(2x+3)(x-7) = 0 ] Setting each factor equal to zero gives: [ 2x+3 = 0 quad text{or} quad x-7 = 0 ] Solving these, we find the roots: [ 2x + 3 = 0 Rightarrow 2x = -3 Rightarrow x = -frac{3}{2} ] [ x - 7 = 0 Rightarrow x = 7 ] Summing the roots: [ -frac{3}{2} + 7 = frac{-3 + 14}{2} = frac{11}{2} ] Thus, the sum of the roots is boxed{frac{11}{2}}.
question:A sphere with center P has radius 4. A triangle with sides of length 13, 14, 15 is situated in space such that each of its sides is tangent to the sphere. What is the distance between P and the plane determined by the triangle? A) 0 B) 2 C) 1 D) 3
answer:1. **Setting up the Problem**: Sphere with radius 4, triangle ABC with sides 13, 14, 15 tangential to the sphere. 2. **Triangle Type and Area**: - Using Heron's formula to calculate the triangle's area: - Semiperimeter, s = frac{13 + 14 + 15}{2} = 21. - Area, A = sqrt{s(s-13)(s-14)(s-15)} = sqrt{21 times 8 times 7 times 6} = sqrt{21 times 336} = 84. 3. **Finding Inradius (r)**: - From area formula with inradius: r = frac{A}{s} = frac{84}{21} = 4. 4. **Distance from Sphere's Center (P) to Plane**: - Let d be the distance from P to plane ABC. - Sphere's inradius due to tangency is 4, so closest point of sphere to plane is 4 units away. - Using geometric configurations or offset: [ d^2 + r^2 = R^2 rightarrow d^2 + 4^2 = 4^2 rightarrow d^2 = 0 rightarrow d = 0. ] - **However, this result conflicts** with the problem setup (sphere cannot be completely inside the triangle if it’s only tangent). Let's revise the calculation: [ PA^2 = r^2 + 4^2 rightarrow 4^2 = r^2 + 4^2 rightarrow r^2 = 0 rightarrow r = 4 ] - Here, it appears there was an error in the previous step: As the sphere is tangent to the plane, and r (radius of sphere’s cross-section) is the same as the sphere's radius. The sphere is thus exactly touching the plane. Therefore, d = r - 4 = 0 (assuming tangency at just one point outside). 5. **Conclusion**: - The distance from the center of the sphere to the plane of the triangle is 0. The final answer is boxed{A) 0}
question:Katie had 9 math problems to finish for homework. She took a bus home with three stops along the way. At the first stop, she completed 2 problems; at the second stop, she completed 3 problems, and at the third stop, she completed 1 problem. If her bus ride lasted 30 minutes and she spent the same amount of time working on the problems between the stops, how many more did she have to do after she got home?
answer:Katie completed 2 problems at the first stop, 3 problems at the second stop, and 1 problem at the third stop. In total, she completed 2 + 3 + 1 = 6 problems on the bus. She started with 9 problems, so after completing 6 on the bus, she had 9 - 6 = boxed{3} problems left to do after she got home.