Yes its correct you did well :)
7 x 10 - 8 is larger by approximately 30
19. It notes or hints to using the quadratic formula because the equation can not be solved by factoring alone. Thus you must use the quadratic formula.
A=-16 B=25 C=3
It is so hard to type a normal equation let alone one of the quadratic formula so I will just attach a picture instead.
However you will end up getting two roots/zeros/x-intercepts of -0.11 and 1.67.
However since it is an application question asking for answers only in the first quadrant you must choose the positive x-intercept.
Therefore the water balloon will land at 1.67 seconds.
20. This question is very simple as it asks you to find a height at a given time. You simply put the given time (1second) into the equation and get your answer.
h=-16(1)^2+25(1)+3
h=12
Also don't mind my little scribble there. :)
-3x+7y=5 (x2) -> -6x+14y=10
-6x+14y=10
-8x+14y=-10
——————— -
2x=20
x=20/20
x=1
Susbstitute x=1,
-8x+14y=-10
-8(1)+14y=-10
-8+14y=-10
14y=-10+8
14y=-2
y=-2/14
y=-1/7
I hope it helps
X cube means it is a third degree function. 2x cube is 1 term and -4 is another. so B.