18. Solve for x by factoring diamond method
10x^2 - 29x - 21 = 0 becomes
(2x - 7)(5x + 3) = 0
x = 7/2, -3/5
A
19. To model this we will do
(x + 9)(x + 9) = 169
distribute
x^2 + 18x - 88 = 0
factor
(x - 4)(x + 22) = 0
The length is 4m
D
20. This can be modeled by
(l)(l +5) = 234
distribute
l^2 + 5l -234 = 0
factor
(l-13)(l+18) = 0
The length is 13
The width is 18
B
21. To find this you divide the x term by 2 and square it so
10/2 = 5
5^2
25
B
22. To find this you divide the x term by 2 and square it so
9/2 = 4.5
4.5^2
81/4
C
Let the first digit of the 2-digit number be x and the second digit be y.
Then the ratio (x/y) equals (1/2). Write a formula for y in terms of x.
The tens digit is 2 more than the units digit. Using the letters x and y, write out the proper equation.
Now solve your two equations simultaneously for x and y.
It should be,
4x-8=2x-10 because you substitute that for y.
Now you do,
4x-2x because you do the opposite of the positive 2x as you bring it to the other side.
That is,
2x-8=10 now you bring the 8 to the other side.
2x=10+8 I added it because I do the opposite and it is a negative 8 so I add.
2x+18 now divide
x=9 that's the answer.
2/3+4/9
denominator= 3*9=27
numerator = (18+12)= 30
therefore the answer is 30/27= 10/9
