Algebra question (please help)?

Question

If the question is X^2 + 3X = 10

then how do you find for X? (plz don't say try random numbers until it works)

please give me an algebraic answer

thank you

Answer 1

X=2 because x(2)times 2=4 and 3 times x (2)=6 and 6 +4=10

hope i helped

Answer 2

remember the quadratic equation...

Answer 3

Use the Quadratic Formula.

X= -b +/ b^2-4ac

----------------------

2a

* Square root over top half of equation

Substitute and simplify.

Answer 4

there are 2 ways, either factoring, in this case it works nicely, but if you havent had a lesson on that it is difficult to explain.

the second is by using the quadratic formula.

Factoring:

X^2+3x=10 (to factor you need one side to =0)

X^2+3x-10=0  in this if you know how to factor, we know that the 2 numbers for x multiply to (-10) and have a difference of (+3). which leaves us with (+5) and (-2)

x^2+5x-2x-10=0   (I changed the 3x to 5x-2x to factor)

x(x+5)-2(x+5)=0 (factor x from the first two, and then(-2) from the last two

(x+5)(x-2)=0 (factor (x-5) from x and -2  (easier to explain in person)

so x=-5, x=2

quadratic formula

x=[-b +/- (sqrt(b^2-4ac) )] /2a

a=1,b=3,c=-10

x= [-3 +/- (sqrt(3^2-(4)(1)(-10)))]/(2)(1)

x=[-3 +/- (sqrt(9+40))]/2

x=[-3 +/- 7]/2

x=4/2   x= -10-2

x=2 ,   x=-5