its the 2nd answer ( you have it marked) :D
Hi hi!!
So, A is correct because it is the same equation just (3+4) is in the front. D is also correct because it is the same question because when a number is for example like 10(3+4) it mean multiplication and in this case you are multiplying. B and C are incorrect because they do not have a total of 70. The original equation, 10x(3+4) = 10x7 = 70.
Correct answers:
A. (3+4)x10
D. 10(4+3)
Check the discriminant (always a good idea).
b^2 - 4ac
b = -19
c = -15
a = 10
(-19)^2 - 4(10)(-15)
361 + 600
961
Yes it can be factored, but if you like, you could use the quadratic formula.
x = [- (-19) +/- sqrt(961)]/(2 * 10)
x = [19 +/- 31 ] / 20
x = (19 + 31/20
x = (50)/20
x = 5/2
x = [19 - 31] / 20
x = [- 12]/20
x = -3/5
Getting the factors is a little tricky.
(x - 5/2)(x + 3/5) = 0
The first factor is found by putting
x - 5/2 in that form and multiplying through by 2
1/2 (2x - 5) The 1/2 comes from multiplying by 2.
The second factor is
1/5 (5x + 3)
So the equation will look like
1/2(2x - 5)1/5(5x + 3) = 0 If you multiply by 2 you get
(2x - 5)1/5(5x + 3) = 0 and now multiply by 5 you get
(2x - 5) (5x + 3)
Check
2x*5x - 25x + 6x - 15
10x^2 - 19x - 15 = 0
So everything works out.
Given:
3 teaspoons of salt for every 5 cups of flour.
How much salt is needed for 15 cups of flour?
This is a proportion problem:
a/b = c/d where ad = bc
3/5 = x/15
3*15 = 5x
45 = 5x
45/5 = x
9 = x
C. 9 teaspoons of salt is needed for 15 cups of flour.
3/5 = 9/15
3*15 = 5*9
45 = 45
Mass = density x volume
1st we need to get the volume
V = (25*10^-1) * (1.8) * (3)
V = 13.5 cm3
mass = 2.53 * 13.5
mass = 34.155 kg
