Quadratic Formula answers help?????

Question

 

2n^2 - 7n -30 = 0
2r^2 +2r - 40 = 0

Answer 1

2n² -7n -30 = 0

2n²- 12n + 5n -30 = 0

Take out common factor 2n and 5

2n(n - 6) + 5(n - 6) = 0

Take out common factor n - 6

(n - 6)(2n + 5) = 0

ab = 0 then a =0 or b = 0

n - 6 = 0 or 2n + 5 = 0

n - 6 = 0

Add 6 to each side

n - 6  + 6 = 6

n = 6

2n + 5 = 0

Subtract 5 from each side

2n +5 - 5 = -5

2n = -5

Multiply each side by 2

n = -5 / 2

The roots of the equation : n = 6 or -5 / 2.

2r²+ 2r  - 40 = 0

2r² +10r -8r  -40 = 0

Take out common factor 2r and -8

2r(r + 5) -8(r + 5) = 0

Take out common factor  r + 5

(r + 5)(2r - 8) = 0

ab = 0 then a =0 or b = 0

r +5 = 0 or 2r - 8 =0

r+ 5 =0

Subtract 5 from each side

r = -5

2r - 8 = 0

Add 8 to each side

2r = 8

Divide each side by 2

r = 4

The roots of the equation -5 and 4.

 

 

 

Answer 2

 

2n^2 - 7n -30 = 0
2n^2 - 12n + 5n -30 = 0
2n (n - 6) + 5 (n - 6) = 0
(2n + 5) (n -6) = 0
2n + 5 =0 or n -6 =0
n = -5/2 or n = 6

Answer 3

Solve by quadratic formula.

1) The equation

Compare it to quadratic formula

Roots are

Discriminant is positive, so there are two real roots.

Solution

2) The equation

Compare it to quadratic formula

Roots are

Discriminant is positive, so there are two real roots.

Solution