When m = what, the value of the quadratic - 5 of the algebraic formula (M + 2) is 20

  When m = what, the value of the quadratic - 5 of the algebraic formula (M + 2) is 20

∵(m+2)^2-5=20.
（m＋2)^2=25.
Square root of both sides:
m+2=±5
m1=-2+5=3；
m2=-2-5=-7.
When m = 3, or M = - 7, it can meet the requirements of question setting

Xiao Ming went to the store to buy one pen, three schoolbags and six notebooks for 119 yuan. After that, he bought four pens, six schoolbags and nine notebooks for 236 yuan. If he bought one pen, one schoolbag and one notebook, how much will it cost?

Let's look at the total price 236-119 = (4 pens, 6 schoolbags, 9 notebooks) - (1 pen, 3 schoolbags, 6 notebooks) = (3 pens, 3 schoolbags, 3 notebooks) = 117
So buy a pen, a bag, a notebook to 117 divided by 3 = 39 yuan

The meteorological department has determined that the temperature will drop by about 6 ℃ for every 1km increase in altitude. Now the surface temperature is 15 ℃, so what is the temperature at 4km altitude?

Let the temperature be x degrees
For every 1km increase in height, the temperature will drop by about 6 ℃
So 4 km is down by 4 × 6 degrees
So 15-x = 4 × 6
15-x=24
x=15-24=-9
So it's - 9 degrees Celsius

-The product of the cube root of 8 and the square root of 9 is ()
A. 6B. ±6C. -6D. 18

-If the cube root of 8 = 3 − 8 = - 2 and the square root of 9 = ± 9 = ± 3, then - 2 × (± 3) = ± 6