Question

pleaase explain!!! solve quadratic equation by completing square..

Answer 1

x^2+2x-7=0

Answer 2

ok

firsat take -7 to LHS:

x^2 + 2x = 7

now you need to write the LHS
in the form (x+b)^2 - c:

to do this divide the coefficient of 2x by 2 and subtract the square of the result:

(x + 1)^2 - 1^2 = 7 ( note that (x+1)^2 - 1 is equivalent to X^2 + 2x)

(x + 1)^2 = 7+1 = 8
now take the square root of both sides of the equation:

x + 1 = sqrt8 or - sqrt8

the rest is easy

Answer 3

* first take -7 to RHS

Answer 4

did u follow that ok?

Answer 5

so the answer is x+1=64

Answer 6

no its the square root of 8 not the square

there are 2 roots

x = sqrt8 - 1 or x = -sqrt8 - 1

which works out to (1.83, -3.83) to 2 places of decimals

Answer 7

im confused .... so it will have two answers? x=1.83-1 and x=-3.83-1

Answer 8

yes quadratic equations often have 2 roots
because their graph can cut the x axis in 2 places