The first 3 are examples of the difference of 2 squares so you use the identity
a^2 - b^2 = (a + b)(a - b)
x^2 - 49 = 0
so (x + 7)(x - 7) = 0
so either x + 7 = 0 or x - 7 = 0
giving x = -7 and 7.
Number 7 reduces to 3x^2 =12, x^2 = 4 so x = +/- 2
Number 8 take out GCf (d) to give
d(d - 2) = 0 so d = 0 , 2
9 and 10 are more difficult to factor
you use the 'ac' method Google it to get more details
2x^2 - 5x + 2
multiply first coefficient by the constant at the end
that is 2 * 2 = 4
Now we want 2 numbers which when multiplied give + 4 and when added give - 5:- -1 and -4 seem promising so we write the equation as:-
2x^2 - 4x - x + 2 = 0
now factor by grouping
2x(x - 2) - 1(x - 2) = 0
(x - 2) is common so
(2x - 1)(x - 2) = 0
and 2x - 1 = 0 or x - 2 = 0 and now you can find x.
The last example is solved in the same way.
Answer:
80%
Step-by-step explanation:
If you divide 52 by 65 you will get a decimal, then multiply by 100% to get the equivalent.
52/65 = 0.8
0.8 x 100 = 80%
Answer:
50 dollars.
Step-by-step explanation:
19 x 25= 475
1,425 - 475= 950
950 divided by 19 is 50.
Question 7:
Diameter = 6.2 cm so Radius = 3.1 cm
A=πr² = 3.14 × 3.1² = 30.1754 cm² = 30.18 cm²
Question 8:
Circumference = 2πr
16π = 2πr
therefore 16 = 2r so r = 8cm
Answer:
6 weeks
Step-by-step explanation:
8 quizzes = 4 weeks
So 2 quizzes/week
It will take her 12/2 weeks (6) to finish 12 quizzes
-Chetan K
