0
2X^2 - 11X - 21 = 0
X = -b +/- sqrt(b^2 -4ac)/2a
a = 2
b = - 11
c = - 21
X = -(-11) +/- sqrt[(-11)^2 - 4(2)(-21)]/2(2)
X = [11 +/- sqrt( 289)]/4
X = [11 +/- 17]/4
X = 7
X = - 3/2
My TI-84 graphs original equation and confirms answers
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What is the quadratic formula for?
The quadratic formula is used to solve the quadratic equation. Many equations in which the variable is squared can be written as a quadratic equation, and then solved with the quadratic formula.
What does quadratic formula find?
When an equation cannot be solved for "x" to find the zeroes, the quadratic formula can be used instead for the same purpose.
Can all quadratics be solved by completing the square?
Completing the square is one method for solving a quadratic equation. A quadratic equation can also be solved by factoring, using the square roots or quadratic formula. Solving quadratic equations by completing the square will always work when solving quadratic equations-You can also use division or even simply take a GCF, set the quantities( ) equal to zero, and subtract or add to solve for the variable
25X2 plus 20X plus 4 equals 0?
This quadratic equation can be solved by three methods: (a) factoring (b) completing the square (c) using the quadratic equation formula.Factoring:25x2+20x+4 = 0(5+2)(5x+2) = 0Solution: x = -2/5 also x = -2/5 (they both have equal roots)
Which part of the quadratic formula tells you whether the quadratic equation can be solved by factoring?
Here are two ways to know if a given quadratic equations can be factored (can be solved by factoring). 1. Calculate the Discriminant D = b^2 - 4ac. When D is a perfect square (its square root is a whole number), then the given equation can be factored. 2. Solve the equation by using the new Diagonal Sum method (Amazon e-book 2010). This method directly finds the 2 real roots without having to factor the equation. Solving usually requires fewer than 3 trials. If this method fails to get the answer, then we can conclude that the equation can not be factored, and consequently the quadratic formula must be used.
