SOLUTION: Solve by using the quadratic formula... 1. 2x^2-7x=5 2. x^2=x+4 3. Find the distance between (7,0) and (-7,0) 4. Solve...x^2+8=17

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Solve by using the quadratic formula... 1. 2x^2-7x=5 2. x^2=x+4 3. Find the distance between (7,0) and (-7,0) 4. Solve...x^2+8=17      Log On


   

Question 86665: Solve by using the quadratic formula...
1. 2x^2-7x=5
2. x^2=x+4
3. Find the distance between (7,0) and (-7,0)
4. Solve...x^2+8=17
Answer by Flake(45) About Me  (Show Source):
You can put this solution on YOUR website!
Solution: Always write in form of "(ax2 + bx + c)=0".
So you can use
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ or %28x%2Ba%29%28x%2Bb%29=0+
to solve
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#1 2x%5E2-7x=5+
2x%5E2-7x-5=0+
x+=+%28-%28-7%29+%2B-+sqrt%28+%28-7%29%5E2-4%2A2%2A%28-5%29+%29%29%2F%282%2A2%29+
x+=+%28+7+%2B-+sqrt%28+49%2B40+%29%29%2F%284%29+
x+=+%28+7+%2B-+sqrt%28+89+%29%29%2F%284%29+
x+=+%28+7+%2B-+9.43%29%29%2F%284%29+
x+=+%28+7+%2B+9.43%29%29%2F%284%29+ = 4.1075+
and
x+=+%287+-+9.43%29%29%2F%284%29+ = -0.6075
****Are you sure you copied the equation right?***
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#2 x%5E2=x%2B4+
x%5E2-x-4=0+
x%5E2-x-4=0+
x+=+%28-%28-1%29+%2B-+sqrt%28+%28-1%29%5E2-4%2A1%2A%28-4%29+%29%29%2F%282%2A1%29+
x+=+%281+%2B-+sqrt%28+1%2B16+%29%29%2F%282%29+
x+=+%281+%2B-+sqrt%28+17+%29%29%2F%282%29+
x+=+%281+%2B-+4.123%29%2F%282%29+
x+=+2.5615+ and x+=+-1.5615+
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#3) Find the distance between (7,0) and (-7,0)
Draw right-triangle
+graph%28+300%2C+300%2C+-10%2C+10%2C+-10%2C+10%2C+x%2B7%29+
Distance is c%5E2+=+a%5E2%2Bb%5E2+
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#4. Solve... x%5E2%2B8=17+
same as #1, and #2 use x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+