SOLUTION: Solve the following quadratic equations by using quadratic formula. 2.1y^2-3.5y=4 a(a+2)=-1 6x^2+5x-4=3x-2 4x^2-14x-27=3

Algebra ->  Algebra  -> Quadratic Equations and Parabolas -> SOLUTION: Solve the following quadratic equations by using quadratic formula. 2.1y^2-3.5y=4 a(a+2)=-1 6x^2+5x-4=3x-2 4x^2-14x-27=3      Log On

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Question 61750This question is from textbook college algebra
: Solve the following quadratic equations by using quadratic formula.
2.1y^2-3.5y=4
a(a+2)=-1
6x^2+5x-4=3x-2
4x^2-14x-27=3This question is from textbook college algebra

Answer by ankor@dixie-net.com(12696) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the following quadratic equations by using quadratic formula.
2.1y^2 - 3.5y = 4
:
2.1y^2 - 3.5y - 4 = 0
I assume you know that the quadratic formula is, here is the first one step-by=step:
a = 2.1; b = -3.5; c = -4
:
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
y+=+%28-%28-3.5%29+%2B-+sqrt%28+%28-3.5%5E2%29-4%2A2.1%2A-4+%29%29%2F%282%2A2.1%29+
y+=+%28%2B3.5+%2B-+sqrt%2812.25+-+%28-33.6%29++%29%29%2F%284.2%29+
y+=+%28%2B3.5+%2B-+sqrt%2812.25+%2B+33.6+%29%29%2F%284.2%29+
y+=+%28%2B3.5+%2B-+sqrt%2845.85+%29%29%2F%284.2%29+
y+=+%28%2B3.5+%2B+6.77%29%2F%284.2%29+
y+=+10.27%2F4.2+
y = +2.446
and
y+=+%28%2B3.5+-+6.77%29%2F%284.2%29+
y+=+-3.27%2F4.2+
y = -.779
:
:
a(a+2) = -1
a^2 + 2a + 1 = 0;
a = 1; b = 2; c = 1,
a+=+%28-2+%2B-+sqrt%28+2%5E2-4%2A1%2A1+%29%29%2F%282%2A1%29+
Complete this like we did above, you will find that it is easy, everything inside the radical cancels out.
a = -1
:
:
Substitute for a,b,c like we did in the 1st one
6x^2 + 5x -4 = 3x - 2
6x^2 + 5x - 3x - 4 + 2 = 0
6x^2 + 2x - 2 = 0
a = 6; b = 2; c = -2
:
:
4x^2 - 14x - 27 = 3
4x^2 - 14x - 27 - 3 = 0
4x^2 - 14x - 30 = 0
a = 4; b =-14; c = -30