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here are 2 expressions:-
a: x^2 + x - 3
b: y^3 - 2y + 6
substitute in these numbers to evaluate
the expressions
3, -3, 0.5, 0.35
a:
1. x² + x - 3
Everywhere you see an x there, replace
it by (-3)
(-3)² + (-3) - 3
Now (-3)² means to multiply (-3) times
(-3). That gives +9, so replace the
(-3)² by 9
9 + (-3) - 3
Now 9 + (-3) gives +6 so replace the
"9 + (-3)" by 6
6 - 3
Now replace 6 - 3 by 3, and that's the
answer,
3
----------------------------------------------
2. x² + x - 3
Everywhere you see an x there, replace
it by (0.5)
(0.5)² + (0.5) - 3
Now (0.5)² means to multiply (0.5) times
(0.5). That gives +0.25, so replace the
(0.5)² by 0.25
0.25 + (0.5) - 3
Now 0.25 + (0.5) gives +0.75 so replace
the "0.25 + (0.5)" by 0.75
0.75 - 3
Now replace 0.75 - 3 by -2.25, and that's
the answer,
-2.25
----------------------------------------------------
3. x² + x - 3
Everywhere you see an x there, replace it
by (0.35)
(0.35)² + (0.35) - 3
Now (0.35)² means to multiply (0.35) times
(0.35). That gives +0.1225, so replace the
(0.35)² by 0.1225
0.1225 + (0.35) - 3
Now 0.1225 + (0.35) gives +0.4725 so replace
the "0.1225 + (0.35)" by 0.4725
0.4725 - 3
Now replace 0.4725 - 3 by -2.5275, and that's
the answer,
-2.5275
========================================================
b:
1. y³ - 2y + 6
Everywhere you see a y there, replace it by
(-3)
(-3)³ - 2(-3) + 6
Now (-3)³ means to multiply (-3) times (-3)
times (-3). That gives
-27, so replace the (-3)³ by -27
-27 - 2(-3) + 6
Now - 2(-3) gives + 6 so replace " - 2(-3) "
by "+ 6"
-27 + 6 + 6
Now -27 + 6 gives -21 so replace the
"-27 + 6" by -21
-21 + 6
Now replace -21 + 6 by -15, and that's
the answer,
-15
----------------------------------------------
2.
y³ - 2y + 6
Everywhere you see a y there, replace it
by (0.5)
(0.5)³ - 2(0.5) + 6
Now (0.5)³ means to multiply
(0.5) times (0.5) times (0.5). That gives
+0.125, so replace the (0.5)³ by 0.125
0.125 - 2(0.5) + 6
Now - 2(0.5) equals - 1 so replace the
" - 2(0.5) " by " - 1 "
0.125 - 1 + 6
Now 0.125 - 1 gives -0.875 so replace the
"0.125 - 1" by -0.875
-0.875 + 6
Now replace -0.875 + 6 by 5.125, and that's
the answer,
5.125
----------------------------------------------------
3. y³ - 2y + 6
Everywhere you see an y there, replace it
by (0.35)
(0.35)³ - 2(0.35) + 6
Now (0.35)³ means to multiply (0.35) times
(0.35) times (0.35). That gives
+0.042875, so replace the
(0.35)³ by 0.042875
0.042875 - 2(0.35) + 6
Now - 2(0.35) gives - 0.7 so replace the
- 2(0.35) by -0.7
0.042875 - 0.7 + 6
Now 0.042875 - 0.7 gives -0.657125 so replace
the "0.042875 - 0.7" by -0.657125
-0.657125 + 6
Now replace -0.657125 + 6 by 5.342875, and
that's the answer,
5.342875
Edwin