how do i solve for x in this problem:(x+5)(x-4)=14?

2009-08-02 5:21 pm

回答 (12)

2009-08-02 5:30 pm
✔ 最佳答案
Then x^2 +x -34=0
x=[-1+&-(1+136)^1/2]/2=5.35235 & -6.35235
GOOD LUCK in summer school.
2009-08-02 5:25 pm
(x + 5)(x - 4) = 14
x(x - 4) + 5(x - 4) 14 = 0
x² - 4x + 5x - 20 = 14
x² + x - 20 = 14
x² + x - 34 = 0

Using the quadratic formula, x = [-b ± √(b² - 4ac)]/(2a), with a = 1, b = 1, c = -34,

x = 5.352 and -6.352 (correct to 3 dp)
2016-11-13 5:07 pm
in case you ever took precalculus or another math classification which covers homes of purposes, you be taught the thank you to be certain the area of the function. between the pink flags to look out for is once you divide with the help of 0. on your expression, while x = 3, the denominator is 0. for that reason, the area is each quantity beside 3. regrettably, the quantity you're attempting to plug in (x = 3) is the only quantity that would not artwork in this function. to be certain this ordinary hand, you0 can graph this function on a TI-80 3. in case you zoom in on the threshold of the graph at x = 3, you will see that there is a sparkling spot there! it is because of the fact, as pronounced above, there only isn't a value of the expression at x = 3. you may say, nicely it looks like the respond ought to be 6, finding on the graph. this concept of what the respond "ought to be" is what limits are all approximately. The values of the function on the left and authentic of x = 3 all flow in the direction of 6 as you get closer and closer. So we are saying the shrink as x is going to 3 is 6. So in spite of if it is no longer technically the respond, 6 is your superb selection. 0 should not be remarkable in any experience. the very superb answer is to declare that the expression is undefined at x = 3. This situation illustrates why 0/0 is named indeterminate. in this situation, 0/0 in a manner equals 6. the theory that 0/0 can equivalent something is quite the essence of calculus.
2009-08-02 6:49 pm
x^2 + x - 20 = 14

x^2 + x - 34 = 0

x = [ - b ± √ ( b ² - 4 a c ) ] / 2 a

x = [ - 1 ± √ ( 1 + 136 ) ] / 2

x = [ - 1 ± √137 ] / 2
2009-08-02 6:18 pm
(x + 5)(x - 4) = 14
x(x) - x(4) + 5(x) - 5(4) = 14
x^2 - 4x + 5x - 20 - 14 = 0
x^2 + x - 34 = 0
x = [-b ±√(b^2 - 4ac)]/(2a)

a = 1
b = 1
c = -34

x = [-1 ±√(1 + 136)]/2
x = [-1 ±√137]/2

∴ x = [-1 ±√137]/2
2009-08-02 5:43 pm
Are you sure the equation isn't (x+5)(x-4)= -14? That comes out to a very clean x = 2 or -3.
2009-08-02 5:29 pm
Expand the left side first:
x^2+x-20=14

Subtract 14 from both sides:
x^2+x-34=0

Use the quadratic equation:

1) x= (-1 + sqrt(1-4(1)(-34)))/(2(1))
x = (-1 + sqrt(137))/2

2) x= (-1 - sqrt(1-4(1)(-34)))/(2(1))
x = (-1- sqrt(137))/2

For the general quadratic equation, for other similar problems, reference:
http://en.wikipedia.org/wiki/Quadratic_equation
2009-08-02 5:27 pm
This is a quadratic equation.
Multiply the x terms.You will get

x^2+x-20=14. i.e., x^2+x-34=0.
The product value must be -34 and the sum must be +1.

There is no such combination of numbers.The result will be a fractional number.You can find the answer by using the formula given in the following link,
2009-08-02 5:31 pm
Expand (x+5)(x-4) Use Foil
x^2 - 4x +5x - 20 = 14 Now bring the 14 to the left. It will be subtracted.
x^2 - 4x +5x -20 - 14 =0
x^2 +x - 34 = 0

You have to use the quadratic equation
a = 1
b = 1
c = - 34

x =( -1 +/- sqr(1 - 4(1)(-34)))/2

x = (- 1 +/- sqr(137) )/2 This would likely do as an answer, but you can go further.

x = (- 1 +/- 11.7)/2
x = 5.35 or
x = - 6.35
2009-08-02 5:27 pm
first subtract 5 from x and 14 then with that result add 4 to both x and the result from before. That will end up with x = something.


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