What is the value of x given that figure adcb
is an isosceles trapezoid?

a: 6
b: 4
c: 1.5
d: 2.4

Step-by-step explanation:

Because the trapezoid is isosceles, the two diagonals are congruent. This can be shown by ASA.

ACD = BDC          Properties of parallel lines.

DC = DC               A line is equal to itself

DBA = CAB           Property of parallel lines.

AC = DB                Parts of Congruent triangles are congruent

3x + 15 = 7x - 9     Add 9 to both sides

3x + 15 + 9 = 7x

3x + 24 = 7x          Subtract 3x from both sides.

24 = 7x - 3x

24 = 4x                  Divide by 4

24/4 = 4x/4

x = 6

step-by-step explanation:

equation

you are asked to write the equation

  expression = 0

using the given expression. when you do that, you have

  2x^2-2x-12 = 0

factoring

you can see that each of the coefficients is even, so a factor of 2 can be removed immediately.

  2(x^2 -x -6) = 0

if you multiply the binomials (x+a)(x+b), you get

  (x +a)(x +b) = x^2 +(a+b)x +ab

this tells you the coefficient of x is the sum of two factors of the constant term. here, that means -1 is the sum of two factors of -6. we want to know those factors so we can factor the trinomial.

  -6 = -1×6 = -2×3 = -3×2 = -6×1

the factor pair that sums to -1 is {-3, 2}, so our factorization is

  2(x -3)(x +2) = 0

solutions

the solutions to this equation are the values of x that make the product zero. a product is zero only when only of the factors of the product is zero. here, that means

  x - 3 = 0

  x = 3 . . . add 3 to both sides of the equation

or

  x +2 = 0

  x = -2 . . . add -2 to both sides of the equation

the solutions to the equation are x=3 or x=-2. both of these values of x satisfy the equation—they make it be true.

answer: you need the equation in the question so i can answer it

step-by-step explanation: