21% were absent, if you divide 146 by 680 and multiply by 100, then round to the nearest whole number, you get 21
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.
Attach picture, where is below
Answer: I subtracted 8 from both sides then divided 3 on both sides
Step-by-step explanation: welcome
Answer:
Step-by-step explanation:
x-7y = -49
i) move x to the right-hand side and change its sign
-7y = -49-x
ii) change the signs on both sides of the equation
7y = 49+x
iii) divide both sides of the equation by 7
iv) use the commutative property to reorder the terms
* commutative property: a+b = b+a
