Try breaking these into sections.
Twice: 2 times
The sum of: add
A number: choose a variable, like x
---Thus "the sum of a number and 4" becomes "add x and 4" which, mathematically, is "x+4"
-----Continuing to put it all together, "Twice the sum of a number and four" becomes "2 times (x+4)" which, mathematically, is "2(x+4)"
Is: equals
-------"Twice the sum of a number and four is" becomes "2(x+4)="
23 less than: subtract 23. This one tends to trick people; "23 less than" will become "__ - 23", NOT "23 - __"
three times the number: 3 times x
---"23 less than three times the number" becomes "subtract 23 from 3 times x" which, mathematically, is "3x-23"
-------So the final phrase: 2(x+4)=3x-23"
Answer:
C and E
Step-by-step explanation:
A. 5* 1/6-5/6
B. 5*2/3=3 1/3
C. 5* 5/3=8 1/3
D5*6/7=4 2/7
E. 5*7/5=7
area = 2x² + 7x - 4
the area (A ) of a rectangle = length × width
A = (2x - 1 )(x + 4 ) ← expand using FOIL
= 2x² + 8x - x - 4 = 2x² + 7x - 4
Answer:
the width is 10 m
Step-by-step explanation:
if the relationship between area and width is
A = 80*w − w²
for an area A=700 m² , we have
700 m² = 80*w − w²
w² - 80*w + 700 m² = 0
aw² + b*w + c = 0
where a=1 , b=-80 and c=700
this quadratic equation has as solution the following formula
w = [-b ± √ ( b² - 4*a*c) ]/(2*a)
replacing values
w = [80 ± √ ( 80² - 4*1*700) ]/(2*1) = (80 ± 60)/2
then
w₁=(80 - 60)/2 = 10 m
w₂ =(80 + 60)/2 = 70 m
since the area has the form A= length * width = 80*w − w² = (80− w)*w
then the length of the rectangle is
length = 80− w
for w₁=10 m → length = 80− 10 = 70 m
for w₁=70 m → length = 80− 70 = 10 m
by definition the shorter side is the width ( and the longer one , the length) , therefore the only possible option is the first one .
Thus the width is 10 m
