2000. Because if you add the 2 it will make 1200, 2+8 is 10 so you carry the 1, and 3+9 is 12 then you add the 1 you got from 10 and you have 13. then you add 1+1 and get 2 and add the 1 you got from 13 so there you have it.

6 0

3 years ago

Find the discriminant, and determine the number of real solutions. then solve x^2 +8x+20=0

vodomira [7]

Answer:

Part 1) The quadratic equation has zero real solutions

Part 2) The solutions are

$x_1=-4+2i$ and $x_2=-4-2i$

Step-by-step explanation:

we know that

The formula to solve a quadratic equation of the form $ax^{2} +bx+c=0$ is equal to

$x=\frac{-b(+/-)\sqrt{b^{2}-4ac}} {2a}$

in this problem we have

$x^{2}+8x+20=0$

$a=1\\b=8\\c=20$

The discriminant is equal to

$D=(b^{2}-4ac)$

If D=0 -----> the quadratic equation has only one real solution

If D>0 -----> the quadratic equation has two real solutions

If D<0 -----> the quadratic equation has two complex solutions

<em>Find the value of D</em>

$D=8^{2}-4(1)(20)=-16$ -----> the quadratic equation has two complex solutions

<em>Find out the solutions</em>

substitute the values of a,b and c in the formula

$x=\frac{-8(+/-)\sqrt{8^{2}-4(1)(20)}} {2(1)}$

$x=\frac{-8(+/-)\sqrt{-16}} {2}$

Remember that

$i=\sqrt{-1}$

$x=\frac{-8(+/-)4i} {2}$

$x_1=\frac{-8(+)4i} {2}=-4+2i$

$x_2=\frac{-8(-)4i} {2}=-4-2i$

8 0

4 years ago

Can 12 cm 12 cm and 28 cm form a triangle

erastova [34]

Using the Theorem of Pythagoras (a² + b² = c²)

Put in the values:

12² + 12² = 28²
Is it correct? (solve)

Nope! Because 12² + 12² = 288, and the square root of 288 is about 17, not 28.

The answer is no, 12cm, 12cm, 28cm cannot form a triangle.

Hopefully this helps! If you have any more questions or don't understand, feel free to DM me, and I'll get back to you ASAP! :)

3 0

3 years ago

Prove: If C⊂A and D⊂B then D−A⊂B−C

nalin [4]

Let $x\in D\setminus A$ , so that $x\in D$ but $x\not\in A$ . Since $D\subset B$ , it follows that $x\in B$ , and since $C\subset A$ , it follows that $x\not\in C$ , which means $x\in B\setminus C$ .

3 0

3 years ago