Math Problem Statement

the positive integer a b c satisfy a^2 + b -c is 100 and a+ b^2 - c is 124 what are they

Solution

We are given two equations involving positive integers aa, bb, and cc:

  1. a2+bc=100a^2 + b - c = 100
  2. a+b2c=124a + b^2 - c = 124

Our goal is to find the values of aa, bb, and cc.

Step 1: Express cc from both equations

From equation (1): c=a2+b100c = a^2 + b - 100 From equation (2): c=a+b2124c = a + b^2 - 124

Now we can set these two expressions for cc equal to each other: a2+b100=a+b2124a^2 + b - 100 = a + b^2 - 124

Step 2: Simplify the equation

Rearrange terms to move everything to one side: a2a+bb2=124+100a^2 - a + b - b^2 = -124 + 100 a2a+bb2=24a^2 - a + b - b^2 = -24 This is the equation we need to solve.

Step 3: Try values for aa and bb

Let's try different values of aa and bb, as the equation is quadratic and involves integers.

Try a=5a = 5:

525+bb2=245^2 - 5 + b - b^2 = -24 255+bb2=2425 - 5 + b - b^2 = -24 20+bb2=2420 + b - b^2 = -24 bb2=44b - b^2 = -44 b2b44=0b^2 - b - 44 = 0 Solve this quadratic equation using the quadratic formula: b=(1)±(1)24(1)(44)2(1)b = \frac{-(-1) \pm \sqrt{(-1)^2 - 4(1)(-44)}}{2(1)} b=1±1+1762b = \frac{1 \pm \sqrt{1 + 176}}{2} b=1±1772b = \frac{1 \pm \sqrt{177}}{2}

Since 177\sqrt{177} is not an integer, a=5a = 5 does not work.

Try a=6a = 6:

626+bb2=246^2 - 6 + b - b^2 = -24 366+bb2=2436 - 6 + b - b^2 = -24 30+bb2=2430 + b - b^2 = -24 bb2=54b - b^2 = -54 b2b54=0b^2 - b - 54 = 0 Solve this quadratic equation using the quadratic formula: b=(1)±(1)24(1)(54)2(1)b = \frac{-(-1) \pm \sqrt{(-1)^2 - 4(1)(-54)}}{2(1)} b=1±1+2162b = \frac{1 \pm \sqrt{1 + 216}}{2} b=1±2172b = \frac{1 \pm \sqrt{217}}{2}

Again, 217\sqrt{217} is not an integer, so a=6a = 6 does not work.

Try a=7a = 7:

727+bb2=247^2 - 7 + b - b^2 = -24 497+bb2=2449 - 7 + b - b^2 = -24 42+bb2=2442 + b - b^2 = -24 bb2=66b - b^2 = -66 b2b66=0b^2 - b - 66 = 0 Solve this quadratic equation using the quadratic formula: b=(1)±(1)24(1)(66)2(1)b = \frac{-(-1) \pm \sqrt{(-1)^2 - 4(1)(-66)}}{2(1)} b=1±1+2642b = \frac{1 \pm \sqrt{1 + 264}}{2} b=1±2652b = \frac{1 \pm \sqrt{265}}{2}

Since 265\sqrt{265} is not an integer either, a=7a = 7 does not work.

Try a=8a = 8:

828+bb2=248^2 - 8 + b - b^2 = -24 648+bb2=2464 - 8 + b - b^2 = -24 56+bb2=2456 + b - b^2 = -24 bb2=80b - b^2 = -80 b2b80=0b^2 - b - 80 = 0 Solve this quadratic equation using the quadratic formula: b=(1)±(1)24(1)(80)2(1)b = \frac{-(-1) \pm \sqrt{(-1)^2 - 4(1)(-80)}}{2(1)} b=1±1+3202b = \frac{1 \pm \sqrt{1 + 320}}{2} b=1±3212b = \frac{1 \pm \sqrt{321}}{2}

Since 321\sqrt{321} is also not an integer, a=8a = 8 does not work.

At this point, trying different values

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Systems of Equations

Formulas

Quadratic equation formula: ax^2 + bx + c = 0
System of equations solving: set equations equal to find common variables

Theorems

Quadratic Formula
Solving Systems of Equations

Suitable Grade Level

Grades 9-11