Minus 16x both sides and add 28 to both sides
x^2-16x+28=0
factor
hmm, what 2 numbers multiply to 28 and add to -16
hmm
1 and 28? nope
2 and 14? yep
since middle term is negative and last tem is positive, both of the factors are negative
(x-14)(x-2)=0
set each to zero
x-14=0
x=14
x-2=0
x=2
x=2 and 14
Since there is no repetition allowed, there are 10 possibilities for the 1st digit, 9 for the 2nd, 8 for the 3rd, and 7 for the 4th. This gives a total of (10)(9)(8)(7) = 5040 four-digit codes.
For all odd digits to be used, there are 5 possibilities for the 1st digit (1,3,5,7,9), 4 for the 2nd, 3 for the 3rd, 2 for the 4th. This gives a total of (5)(4)(3)(2) = 120 codes that only use odd digits.
Therefore there are 5040 - 120 = 4920 codes that do not consist of all odd digits. The probability is 4920/5040 = 41/42.
Answer:
164
Step-by-step explanation:
2x+7+5x+12=180
7x+19=180
7x+180-19
7x=171
---- ----
7 7
x=164
B. 31°, 43°, 106°
since all angles of a triangle add up to 180°, you combine all of the equations to equal 180 and solve for X. the equation you would get it 3x+1+11x-4+5x-7=180. this simplifies to 19x-10=180. then you solve for x, and it is 10. then, you plug 10 into all of the equations separately to find the angles. therefore, the answer is B