Answer:
step 2
and then also in step 3 compensating the error in step 2
Step-by-step explanation:
I think I just answered this for another post.
sin(a - b) = sin(a)cos(b) - cos(a)sin(b)
so, step 1 is correct :
sin(A - 3pi/2) = sin(A)cos(3pi/2) - cos(A)sin(3pi/2)
but step 2 suddenly and incorrectly switched that central "-" to a "+".
yes, sin(3pi/2) = -1, but that is still an explicit factor in step 2. so it was not used to flip the central operation from subtraction to addition, and therefore this change was a mistake.
then, in step 3, another error was made by just ignoring the "-" sign of "-1" and still keeping the central "+" operation. this error compensated for the error in step 2 bringing us back by pure chance to the right result.
Answer:
a) x =3 and x=5
c) x =-1 and 
i) x =0 and 
Step-by-step explanation:
a)
Given that the quadratic equation
x² - 8x +15 =0
The factors of 15 = 5 × 3
x² - 5x -3x +15 =0
x(x -5) -3(x-5) =0
(x-3)(x-5) =0
x =3 and x=5
c)
3 x² + 10 x +7 =0
⇒ 3x² + 3x + 7x +7 =0
⇒ 3x (x +1) +7(x+1) =0
⇒ (x+1) ( 3 x +7) =0
⇒ x =-1 and
i)
2 x ² + 9 x =0
⇒ x( 2 x + 9) =0
⇒ x =0 and 2 x = -9
⇒ x =0 and
